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Toyama Prefectural Public High School Entrance Examination - Science study materials
Toyama Prefectural Public High School Entrance Examination - Science study resources

Toyama Prefectural Public High School Entrance Examination - Science practice questions

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Question 1Physics (力と運動, 電流, 光と音, エネルギー)

A car travels 120 m along a straight road in 8.0 s at a constant speed. What is its speed?

  1. 0.067 m/s
  2. 128 m/s
  3. 960 m/s
  4. 15 m/s Correct answer.

Explanation

Speed is distance divided by time, so 120 m ÷ 8.0 s = 15 m/s. This value means the car covers 15 m in every second of its motion. Dividing distance by time, rather than multiplying, is essential because speed is a rate per unit time.

Question 2Physics (力と運動, 電流, 光と音, エネルギー)

A book lies at rest on a horizontal table. Which pair of forces is an action–reaction pair according to Newton's third law?

  1. The force of the book pressing down on the table and the force of the table pressing up on the book Correct answer.
  2. The normal force acting on the book and the weight of the table
  3. The weight of the book and the friction force between the book and the table
  4. The weight of the book acting vertically downwards and the normal force from the table acting vertically upwards on the book

Explanation

Newton's third-law pairs act on two different objects, are equal in size, opposite in direction and are of the same kind. The book presses on the table and the table presses back on the book with an equal and opposite force, so these form a pair. The book's weight and the normal force both act on the book, so they balance but are not an action–reaction pair.

Question 3Physics (力と運動, 電流, 光と音, エネルギー)

A current of 0.30 A flows through a resistor of resistance 20 Ω. What is the voltage across the resistor?

  1. 67 V
  2. 20.3 V
  3. 0.015 V
  4. 6.0 V Correct answer.

Explanation

Ohm's law states that voltage equals current multiplied by resistance, V = I × R. Substituting gives 0.30 A × 20 Ω = 6.0 V. Voltage grows as either the current or the resistance increases, so multiplication is the correct operation.

Question 4Physics (力と運動, 電流, 光と音, エネルギー)

A ray of light strikes a flat mirror making an angle of 30° with the mirror surface. What angle does the reflected ray make with the mirror surface?

  1. 120°
  2. 60°
  3. 30° Correct answer.
  4. 90°

Explanation

Angles in reflection are measured from the normal, which is perpendicular to the mirror surface. A ray 30° above the surface is 60° from the normal, so the reflected ray also leaves at 60° from the normal. Measured back from the surface, that is 90° − 60° = 30°, the same as the incident ray's angle to the surface.

Question 5Physics (力と運動, 電流, 光と音, エネルギー)

A sound wave with a frequency of 500 Hz travels through air at 340 m/s. What is its wavelength?

  1. 1.5 m
  2. 0.0015 m
  3. 0.68 m Correct answer.
  4. 170 m

Explanation

For any wave, speed equals frequency multiplied by wavelength, so wavelength equals speed divided by frequency. Here 340 m/s ÷ 500 Hz = 0.68 m. This means successive compressions of the sound wave are 0.68 m apart in the air.

Question 6Physics (力と運動, 電流, 光と音, エネルギー)

A net force of 12 N acts on a 4.0 kg object sliding on a frictionless surface. What is the magnitude of its acceleration?

  1. 48 m/s²
  2. 3.0 m/s² Correct answer.
  3. 8.0 m/s²
  4. 0.33 m/s²

Explanation

Newton's second law gives acceleration as the net force divided by the mass, a = F ÷ m. Dividing 12 N by 4.0 kg gives 3.0 m/s². The acceleration is in the same direction as the net force and does not depend on how fast the object is already moving.

Question 7Physics (力と運動, 電流, 光と音, エネルギー)

A ball of mass 0.50 kg is held 2.0 m above the ground. Taking g = 10 m/s², what is its gravitational potential energy relative to the ground?

  1. 1.0 J
  2. 5.0 J
  3. 10 J Correct answer.
  4. 40 J

Explanation

Gravitational potential energy is calculated as mgh, the product of mass, gravitational field strength and height. Substituting gives 0.50 kg × 10 m/s² × 2.0 m = 10 J. If the ball were released, this stored energy would be converted into kinetic energy as it fell.

Question 8Physics (力と運動, 電流, 光と音, エネルギー)

A 6 Ω resistor and a 3 Ω resistor are connected in series. What is the combined resistance of the pair?

  1. 9 Ω Correct answer.
  2. 18 Ω
  3. 2.0 Ω
  4. 4.5 Ω

Explanation

In a series circuit the same current passes through every resistor, and the total resistance is the sum of the individual resistances. Adding gives 6 Ω + 3 Ω = 9 Ω. The combined resistance is therefore larger than either resistor on its own.

Question 9Physics (力と運動, 電流, 光と音, エネルギー)

In a hydroelectric power station, water stored behind a dam flows down through pipes and spins turbines connected to generators. Which chain best describes the main energy conversions?

  1. Light energy → thermal energy → gravitational potential energy
  2. Electrical energy → chemical energy in a battery → kinetic energy of a motor
  3. Gravitational potential energy → kinetic energy → electrical energy Correct answer.
  4. Chemical energy → sound energy → light energy

Explanation

Water held high in the reservoir stores gravitational potential energy. As it falls and speeds through the pipes this becomes kinetic energy, and the spinning generator converts the motion into electrical energy. Some energy is also lost to the surroundings as heat and sound at each stage.

Question 10Physics (力と運動, 電流, 光と音, エネルギー)

A train starting from rest increases its speed steadily to 12 m/s over 6.0 s. What distance does it travel during these 6.0 s?

  1. 72 m
  2. 12 m
  3. 18 m
  4. 36 m Correct answer.

Explanation

With uniform acceleration the average speed is the mean of the initial and final speeds, here (0 + 12) ÷ 2 = 6.0 m/s. Distance is average speed multiplied by time, so 6.0 m/s × 6.0 s = 36 m. The same result comes from the area of the triangular speed–time graph, ½ × 6.0 × 12.

Question 11Physics (力と運動, 電流, 光と音, エネルギー)

A ray of light passes from air into a glass block at an angle to the surface. Which description of what happens to the ray is correct?

  1. The light slows down and bends toward the normal Correct answer.
  2. The light slows down and bends away from the normal
  3. The light speeds up and bends away from the normal
  4. The light keeps the same speed and bends toward the normal

Explanation

Light travels more slowly in glass than in air. When a ray enters a slower medium at an angle, it bends toward the normal drawn at the boundary. This change of direction at the boundary is called refraction, and the frequency of the light does not change.

Question 12Physics (力と運動, 電流, 光と音, エネルギー)

A steady current of 0.40 A flows through a lamp for 5.0 minutes. How much charge passes through the lamp?

  1. 120 C Correct answer.
  2. 2.0 C
  3. 0.080 C
  4. 240 C

Explanation

Charge is current multiplied by time, Q = I × t. The time must be converted to seconds: 5.0 min = 300 s, so Q = 0.40 A × 300 s = 120 C. Using minutes rather than seconds would give a value sixty times too small.

Question 13Physics (力と運動, 電流, 光と音, エネルギー)

A box is pushed across a rough horizontal floor at a steady speed by a horizontal force of 15 N. What is the friction force acting on the box?

  1. more than 15 N directed opposite to the motion
  2. 0 N because the box is moving
  3. 15 N directed in the same direction as the motion
  4. 15 N directed opposite to the motion Correct answer.

Explanation

Steady speed means the velocity is not changing, so the forces on the box are balanced and the net force is zero. The friction force must therefore be equal in size to the pushing force, 15 N, and opposite in direction. Friction acts against the relative sliding of the two surfaces.

Question 14Physics (力と運動, 電流, 光と音, エネルギー)

An electric heater rated at 1200 W is used for 10 minutes. How much electrical energy does it use, expressed in kilowatt-hours?

  1. 0.20 kWh Correct answer.
  2. 0.020 kWh
  3. 0.72 kWh
  4. 12 kWh

Explanation

Energy in kilowatt-hours equals power in kilowatts multiplied by time in hours. Here 1200 W = 1.2 kW and 10 min = 1/6 h, so the energy is 1.2 × 1/6 = 0.20 kWh. The same energy is 720 000 J, since 0.20 kWh × 3 600 000 J/kWh gives that value.

Question 15Physics (力と運動, 電流, 光と音, エネルギー)

A person claps and hears the echo from a distant cliff 1.2 s later. Taking the speed of sound in air as 340 m/s, how far away is the cliff?

  1. 102 m
  2. 408 m
  3. 283 m
  4. 204 m Correct answer.

Explanation

The sound travels to the cliff and back, so the total distance covered is speed × time = 340 m/s × 1.2 s = 408 m. This total is twice the distance to the cliff, so the cliff is 408 ÷ 2 = 204 m away. Forgetting to halve the result is the usual mistake in echo problems.

Question 16Physics (力と運動, 電流, 光と音, エネルギー)

A ball is thrown vertically upward and then moves under the influence of gravity alone. At the highest point of its flight, which statement is correct?

  1. Velocity is zero and acceleration is zero
  2. Velocity is zero and acceleration is 9.8 m/s² upward
  3. Velocity is zero and acceleration is 9.8 m/s² downward Correct answer.
  4. Velocity is maximum and acceleration is zero

Explanation

At the highest point the ball momentarily stops, so its velocity is zero, but gravity is still acting on it. A body moving freely near the Earth's surface always has an acceleration of about 9.8 m/s² directed downward, whatever its speed or direction of motion. That downward acceleration is why the ball immediately begins to fall back.

Question 17Physics (力と運動, 電流, 光と音, エネルギー)

An electric motor is supplied with 500 J of electrical energy and delivers 350 J of useful work. What is the efficiency of the motor?

  1. 35%
  2. 30%
  3. 70% Correct answer.
  4. 143%

Explanation

Efficiency compares the useful energy output with the total energy input: 350 J ÷ 500 J = 0.70, or 70%. The remaining 150 J is transferred to the surroundings, mainly as heat and sound. An efficiency above 100% is impossible because it would mean more energy came out than went in.

Question 18Physics (力と運動, 電流, 光と音, エネルギー)

A 4 Ω resistor and an 8 Ω resistor are connected in series with a 12 V battery. What is the voltage across the 8 Ω resistor?

  1. 8 V Correct answer.
  2. 4 V
  3. 12 V
  4. 6 V

Explanation

The total resistance is 4 + 8 = 12 Ω, so the current is 12 V ÷ 12 Ω = 1.0 A. In a series circuit the same current flows through both resistors, so the voltage across the 8 Ω resistor is 1.0 A × 8 Ω = 8 V. The larger resistance takes the larger share of the supply voltage.

Question 19Physics (力と運動, 電流, 光と音, エネルギー)

An object is placed on the axis of a convex lens at a distance greater than twice the focal length. What kind of image is formed?

  1. Virtual, upright and larger than the object
  2. Real, inverted and larger than the object
  3. Real, inverted and smaller than the object Correct answer.
  4. Virtual, upright and the same size as the object

Explanation

With a convex lens, an object placed beyond 2f forms a real image between f and 2f on the other side of the lens. The rays actually converge there, so the image is inverted, and because it lies closer to the lens than the object does, it is smaller. Real images can be caught on a screen, unlike virtual images.

Question 20Physics (力と運動, 電流, 光と音, エネルギー)

A cyclist covers the first 300 m of a journey at 5.0 m/s and the next 200 m at 4.0 m/s. What is the average speed for the whole journey?

  1. 9.0 m/s
  2. 4.5 m/s Correct answer.
  3. 4.0 m/s
  4. 5.0 m/s

Explanation

Average speed is total distance divided by total time, so the time for each stage must be found first. The first stage takes 300 ÷ 5.0 = 60 s and the second takes 200 ÷ 4.0 = 50 s, giving 500 m in 110 s. The average speed is therefore 500 ÷ 110 ≈ 4.5 m/s, which lies between the two stage speeds and is not their simple average.

Question 21Physics (力と運動, 電流, 光と音, エネルギー)

Which of the following quantities is measured in newtons?

  1. The mass of the object
  2. The volume of the object
  3. The density of the object
  4. The weight of the object Correct answer.

Explanation

The newton is the unit of force, and weight is the force of gravity acting on an object. Mass is measured in kilograms, density in grams per cubic centimetre or kilograms per cubic metre, and volume in cubic metres or litres. Weight and mass are therefore different quantities with different units.

Question 22Physics (力と運動, 電流, 光と音, エネルギー)

A ball of mass 2.0 kg is released from rest 5.0 m above the ground. Taking g = 10 m/s² and ignoring air resistance, what is its speed just before it reaches the ground?

  1. 14 m/s
  2. 5.0 m/s
  3. 10 m/s Correct answer.
  4. 50 m/s

Explanation

The gravitational potential energy lost is mgh = 2.0 × 10 × 5.0 = 100 J, and this becomes kinetic energy during the fall. Setting ½mv² equal to 100 J gives v² = 100, so v = 10 m/s. The mass cancels out of the equation, so a ball of any mass released from the same height would land at the same speed.

Question 23Physics (力と運動, 電流, 光と音, エネルギー)

A sound wave travelling through air has its amplitude increased while its frequency is kept the same. Which property of the sound changes?

  1. Its wavelength
  2. Its loudness Correct answer.
  3. Its pitch
  4. Its speed in air

Explanation

The amplitude of a sound wave corresponds to the size of the pressure variations and is heard as loudness. Frequency determines pitch, and since the frequency is unchanged the pitch stays the same. The speed of sound in air depends on the medium and its temperature, not on amplitude, so the wavelength is also unchanged.

Question 24Physics (力と運動, 電流, 光と音, エネルギー)

A coil of wire wound on a soft-iron core is used as an electromagnet. Which change makes its magnetic field stronger?

  1. Increasing the number of turns of wire in the coil Correct answer.
  2. Decreasing the current flowing through the coil
  3. Replacing the iron core with a plastic rod of the same size
  4. Reducing the number of turns of wire in the coil

Explanation

The strength of an electromagnet increases with the current through the coil and with the number of turns of wire. It is also much stronger when a magnetic material such as soft iron forms the core. Increasing the number of turns therefore strengthens the field, while reversing the current merely reverses the poles.

Question 25Physics (力と運動, 電流, 光と音, エネルギー)

When the voltage across a resistor is raised from 2.0 V to 6.0 V, the current through it increases by 0.20 A. What is the resistance of the resistor?

  1. 40 Ω
  2. 20 Ω Correct answer.
  3. 30 Ω
  4. 10 Ω

Explanation

The resistance is constant, so the change in voltage and the change in current are related by ΔV = R × ΔI. The voltage rises by 4.0 V while the current rises by 0.20 A, giving R = 4.0 ÷ 0.20 = 20 Ω. Checking with Ohm's law, 2.0 V gives 0.10 A and 6.0 V gives 0.30 A, a difference of 0.20 A as stated.

Question 26Physics (力と運動, 電流, 光と音, エネルギー)

A car travels 120 m along a straight road at a steady speed in 8.0 s. What is its speed?

  1. 0.067 m/s
  2. 960 m/s
  3. 15 m/s Correct answer.
  4. 128 m/s

Explanation

Speed is the distance travelled divided by the time taken, so 120 m ÷ 8.0 s = 15 m/s. Because the motion is at a steady speed, this value is the speed throughout the journey.

Question 27Physics (力と運動, 電流, 光と音, エネルギー)

An object is moving in a straight line at a constant speed. Which statement describes the net force acting on the object?

  1. It is constant and acts in the direction of motion
  2. It is equal to the weight of the object
  3. It is zero Correct answer.
  4. It increases steadily as the object moves

Explanation

Newton's first law says an object keeps moving at constant velocity only when the forces on it are balanced, so the net force must be zero. A non-zero net force would change the object's speed or direction.

Question 28Physics (力と運動, 電流, 光と音, エネルギー)

Two lamps are connected in series with a battery, and a current of 0.30 A flows through the first lamp. What current flows through the second lamp?

  1. 0.15 A
  2. 0 A, because the current is used up
  3. 0.60 A
  4. 0.30 A Correct answer.

Explanation

In a series circuit there is only one path for the charge, so the current is the same at every point. The 0.30 A passes through both lamps without change.

Question 29Physics (力と運動, 電流, 光と音, エネルギー)

Two lamps are connected in parallel to a 6.0 V battery. What is the voltage across each lamp?

  1. 6.0 V Correct answer.
  2. 12 V
  3. It depends on the resistance of each lamp
  4. 3.0 V

Explanation

In a parallel circuit each branch is connected directly across the supply, so every branch has the full supply voltage across it. Each lamp therefore receives 6.0 V whatever its resistance.

Question 30Physics (力と運動, 電流, 光と音, エネルギー)

A motor does 300 J of work in 5.0 s. What is its power output?

  1. 305 W
  2. 1500 W
  3. 60 W Correct answer.
  4. 0.017 W

Explanation

Power is the rate of doing work, P = W ÷ t, so 300 J ÷ 5.0 s = 60 W. This value tells how much energy the motor transfers each second.

Question 31Physics (力と運動, 電流, 光と音, エネルギー)

A girl stands 1.5 m in front of a flat mirror. How far behind the mirror does her image appear to be?

  1. 1.5 m Correct answer.
  2. 3.0 m
  3. 0.75 m
  4. The image position depends on the size of the mirror

Explanation

A plane mirror forms a virtual image as far behind the mirror as the object is in front of it. With the girl 1.5 m in front, the image appears 1.5 m behind the mirror.

Question 32Physics (力と運動, 電流, 光と音, エネルギー)

Two musical notes are played with the same loudness but different frequencies. What is the difference between the two notes?

  1. Only one of them can travel through air
  2. Their speeds in air are different
  3. Their pitches are different Correct answer.
  4. Their wavelengths are the same

Explanation

Frequency determines pitch: a higher frequency is heard as a higher note. Both notes travel at the same speed in the same air, so their wavelengths must differ because wavelength = speed ÷ frequency.

Question 33Physics (力と運動, 電流, 光と音, エネルギー)

Which arrangement correctly describes an instrument used to measure the current flowing through a circuit?

  1. An ammeter connected in series with the component Correct answer.
  2. A voltmeter connected in series with the component
  3. An ammeter connected in parallel with the component
  4. A voltmeter connected in parallel with the component

Explanation

Current is measured with an ammeter, which must be connected in series so that the current to be measured passes through it. A voltmeter measures potential difference and is connected in parallel.

Question 34Physics (力と運動, 電流, 光と音, エネルギー)

A cyclist's speed increases steadily from 4.0 m/s to 10 m/s in 3.0 s. What is the magnitude of her acceleration?

  1. 4.7 m/s²
  2. 3.3 m/s²
  3. 6.0 m/s²
  4. 2.0 m/s² Correct answer.

Explanation

Acceleration is the change in velocity divided by the time taken: (10 − 4.0) ÷ 3.0 = 2.0 m/s². Since the speed rises steadily, the acceleration is constant.

Question 35Physics (力と運動, 電流, 光と音, エネルギー)

A stone is dropped from rest from a height of 45 m. Taking g = 10 m/s² and ignoring air resistance, how long does it take to reach the ground?

  1. 4.5 s
  2. 9.0 s
  3. 3.0 s Correct answer.
  4. 2.1 s

Explanation

For an object released from rest, h = ½gt², so t = √(2h ÷ g) = √(90 ÷ 10) = 3.0 s. The mass of the stone does not affect the time of fall when air resistance is ignored.

Question 36Physics (力と運動, 電流, 光と音, エネルギー)

The speed of a moving car is doubled while its mass stays the same. How does its kinetic energy change?

  1. It becomes four times as large Correct answer.
  2. It becomes twice as large
  3. It becomes sixteen times as large
  4. It becomes half as large

Explanation

Kinetic energy is ½mv², so it is proportional to the square of the speed. Doubling the speed multiplies the kinetic energy by 2² = 4.

Question 37Physics (力と運動, 電流, 光と音, エネルギー)

A ball is released from rest at a height of 5.0 m above the ground. Ignoring air resistance and taking g = 10 m/s², what is its speed just before it hits the ground?

  1. 5.0 m/s
  2. 7.1 m/s
  3. 10 m/s Correct answer.
  4. 25 m/s

Explanation

The potential energy lost becomes kinetic energy: mgh = ½mv², so v = √(2gh) = √(2 × 10 × 5.0) = 10 m/s. The mass cancels out of the equation.

Question 38Physics (力と運動, 電流, 光と音, エネルギー)

Two forces of 3.0 N and 4.0 N act at right angles to each other at the same point on an object. What is the magnitude of the resultant force?

  1. 7.0 N
  2. 12 N
  3. 5.0 N Correct answer.
  4. 1.0 N

Explanation

Two perpendicular forces combine by the Pythagorean rule: √(3.0² + 4.0²) = √25 = 5.0 N. The resultant points diagonally between the two forces.

Question 39Physics (力と運動, 電流, 光と音, エネルギー)

A skater pushes backwards against a wall and moves away from it. Which statement describes the pair of forces involved?

  1. The skater pushes the wall harder than the wall pushes back on the skater
  2. The wall pushes the skater only after the skater begins to move
  3. The two forces are equal in size and opposite in direction Correct answer.
  4. The two forces act on the same object and cancel each other out

Explanation

Newton's third law states that when one body exerts a force on another, the second exerts an equal force in the opposite direction on the first. The skater moves because the force from the wall acts on the skater, not because the forces are unequal.

Question 40Physics (力と運動, 電流, 光と音, エネルギー)

A 6.0 Ω resistor and a 3.0 Ω resistor are connected in parallel. What is the combined resistance?

  1. 0.50 Ω
  2. 9.0 Ω
  3. 4.5 Ω
  4. 2.0 Ω Correct answer.

Explanation

For resistors in parallel, 1/R = 1/6.0 + 1/3.0 = 0.50, so R = 2.0 Ω. The combined resistance is smaller than the smallest individual resistance.

Question 41Physics (力と運動, 電流, 光と音, エネルギー)

An electric appliance is connected to a 100 V supply and a current of 0.50 A flows through it. What is its power consumption?

  1. 100 W
  2. 50 W Correct answer.
  3. 0.50 W
  4. 200 W

Explanation

Electrical power is P = VI = 100 V × 0.50 A = 50 W. This is the energy converted by the appliance each second.

Question 42Physics (力と運動, 電流, 光と音, エネルギー)

A straight wire carrying a current is placed in a magnetic field so that the wire is parallel to the field lines. What is the magnitude of the force on the wire?

  1. Equal to the current multiplied by the field strength
  2. The same as when the wire is perpendicular to the field
  3. Greatest when the wire is parallel to the field
  4. Zero Correct answer.

Explanation

The magnetic force on a current-carrying wire is largest when the wire is perpendicular to the field and falls to zero when the wire is parallel to the field lines. With no component of the field perpendicular to the current, no force acts.

Question 43Physics (力と運動, 電流, 光と音, エネルギー)

A sound wave has a frequency of 500 Hz and a wavelength of 0.68 m. What is its speed?

  1. 340 m/s Correct answer.
  2. 500.68 m/s
  3. 735 m/s
  4. 0.0014 m/s

Explanation

For a wave, speed = frequency × wavelength = 500 Hz × 0.68 m = 340 m/s. This is the usual speed of sound in air.

Question 44Physics (力と運動, 電流, 光と音, エネルギー)

A pendulum bob swings back and forth. Ignoring air resistance, at which point is its kinetic energy greatest?

  1. At every point, because energy is conserved
  2. At the lowest point of the swing Correct answer.
  3. At the highest point of the swing
  4. Halfway between the highest and lowest points

Explanation

The bob's potential energy is smallest at the lowest point, so most of the energy is kinetic there and the bob moves fastest. At the highest points the bob is momentarily at rest.

Question 45Physics (力と運動, 電流, 光と音, エネルギー)

Two lamps are connected in parallel to a battery. One lamp breaks and no current can flow through it. What happens to the other lamp?

  1. It becomes brighter, since all the current now passes through it
  2. It goes out, because the circuit is broken
  3. It flickers, because the current changes direction
  4. It stays lit, because its branch is still complete Correct answer.

Explanation

In a parallel circuit each lamp is on its own branch connected directly to the battery, so a broken branch does not stop the current in the other branch. The working lamp therefore stays lit and keeps the same voltage across it.

Question 46Physics (力と運動, 電流, 光と音, エネルギー)

In a circuit, a 4.0 Ω resistor is connected in series with a parallel pair made of a 6.0 Ω and a 3.0 Ω resistor. The combination is connected to a 12 V battery of negligible internal resistance. What is the current through the 4.0 Ω resistor?

  1. 4.0 A
  2. 1.0 A
  3. 2.0 A Correct answer.
  4. 3.0 A

Explanation

The parallel pair has resistance 1 ÷ (1/6.0 + 1/3.0) = 2.0 Ω, so the total resistance is 4.0 + 2.0 = 6.0 Ω. The current from the battery is 12 V ÷ 6.0 Ω = 2.0 A, and this whole current passes through the series 4.0 Ω resistor.

Question 47Physics (力と運動, 電流, 光と音, エネルギー)

An object starts from rest and accelerates uniformly at 2.0 m/s² for 4.0 s. It then travels at the constant speed it has reached for a further 3.0 s. What is the total distance travelled?

  1. 24 m
  2. 56 m
  3. 40 m Correct answer.
  4. 16 m

Explanation

After 4.0 s the speed is 2.0 × 4.0 = 8.0 m/s, so the first stage covers ½ × 4.0 × 8.0 = 16 m. The second stage adds 8.0 × 3.0 = 24 m, giving 16 + 24 = 40 m in total.

Question 48Physics (力と運動, 電流, 光と音, エネルギー)

A ball is thrown vertically upward with a speed of 20 m/s. Taking g = 10 m/s² and ignoring air resistance, how long is the ball in the air before it returns to the thrower's hand?

  1. 4.0 s Correct answer.
  2. 8.0 s
  3. 2.0 s
  4. 1.0 s

Explanation

The time to reach the highest point is v ÷ g = 20 ÷ 10 = 2.0 s, and the downward journey takes the same time because the motion is symmetric. The total time in the air is therefore 4.0 s.

Question 49Physics (力と運動, 電流, 光と音, エネルギー)

Light travelling inside a glass block reaches the boundary with the air at an angle of 45° to the normal. The critical angle for this glass is 42°. What happens to the light at the boundary?

  1. It is totally reflected back into the glass Correct answer.
  2. It passes into the air along the boundary surface
  3. It is completely absorbed by the air
  4. Most of it passes into the air, bending away from the normal

Explanation

Total internal reflection occurs when light travels from a denser medium to a less dense one and the angle of incidence exceeds the critical angle. Here 45° is greater than 42°, so no light escapes and the ray is reflected back into the glass.

Question 50Physics (力と運動, 電流, 光と音, エネルギー)

An electric kettle rated at 1200 W is used on a 100 V supply. What is the resistance of its heating element?

  1. 0.083 Ω
  2. 12 Ω
  3. 120 Ω
  4. 8.3 Ω Correct answer.

Explanation

The current is P ÷ V = 1200 W ÷ 100 V = 12 A, so the resistance is R = V ÷ I = 100 V ÷ 12 A ≈ 8.3 Ω. The same result comes directly from R = V² ÷ P = 10000 ÷ 1200.