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Gifu Entrance Science practice questions

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Question 1Physics - Mechanics (motion, forces, energy, momentum)

A ball is thrown vertically upward and rises until its speed becomes zero at the highest point. Which statement about the ball at that instant is correct?

  1. Its acceleration is directed downward and equals about 9.8 m/s². Correct answer.
  2. Its acceleration is directed upward and equals about 9.8 m/s².
  3. Its acceleration is zero because its velocity is zero.
  4. Its acceleration is downward but smaller than 9.8 m/s².

Explanation

At the top the velocity is momentarily zero, but the velocity is still changing from upward to downward. Gravity acts throughout the motion, so the acceleration remains about 9.8 m/s² downward the whole time.

Question 2Physics - Mechanics (motion, forces, energy, momentum)

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

  1. 20 m/s
  2. 15 m/s Correct answer.
  3. 12 m/s
  4. 8.0 m/s

Explanation

For constant speed, speed equals distance divided by time. Dividing 120 m by 8.0 s gives 15 m/s.

Question 3Physics - Mechanics (motion, forces, energy, momentum)

Which quantity is a vector?

  1. Mass
  2. Displacement Correct answer.
  3. Distance travelled
  4. Time interval

Explanation

A vector needs both magnitude and direction. Displacement specifies how far and in which direction an object moved, while mass, distance, and time are scalars with magnitude only.

Question 4Physics - Mechanics (motion, forces, energy, momentum)

A 4.0 kg block rests on a horizontal table. What is the magnitude of the normal force the table exerts on the block? (g = 9.8 m/s²)

  1. 9.8 N
  2. 4.0 N
  3. 19.6 N
  4. 39 N Correct answer.

Explanation

On a horizontal surface with no vertical acceleration, the normal force balances the weight. Weight equals mg = 4.0 × 9.8 = 39.2 N, so the normal force is about 39 N.

Question 5Physics - Mechanics (motion, forces, energy, momentum)

A moving object has kinetic energy. If its speed doubles while its mass stays the same, its kinetic energy becomes

  1. four times as large Correct answer.
  2. twice as large
  3. half as large
  4. unchanged

Explanation

Kinetic energy equals ½mv², so it depends on the square of the speed. Doubling the speed multiplies the kinetic energy by 2² = 4.

Question 6Physics - Mechanics (motion, forces, energy, momentum)

A 2.0 kg cart moving at 3.0 m/s collides with a stationary 4.0 kg cart, and they stick together. What is their common speed just after the collision?

  1. 1.5 m/s
  2. 1.0 m/s Correct answer.
  3. 3.0 m/s
  4. 2.0 m/s

Explanation

Momentum is conserved in the collision. Initial momentum is 2.0 × 3.0 = 6.0 kg·m/s, and the combined mass is 6.0 kg, so the common speed is 6.0 ÷ 6.0 = 1.0 m/s.

Question 7Physics - Mechanics (motion, forces, energy, momentum)

According to Newton's third law, when a swimmer pushes backward on the water, the water

  1. pushes forward on the swimmer with a smaller force
  2. pushes backward on the swimmer with an equal-magnitude force
  3. exerts no force on the swimmer
  4. pushes forward on the swimmer with an equal-magnitude force Correct answer.

Explanation

Newton's third law states that forces come in equal-magnitude, opposite-direction pairs on the two interacting bodies. The water pushes forward on the swimmer, which propels the swimmer ahead.

Question 8Physics - Mechanics (motion, forces, energy, momentum)

A worker lifts a 10 kg box vertically through 2.0 m at constant speed. What is the work done by the lifting force? (g = 9.8 m/s²)

  1. 196 J Correct answer.
  2. 490 J
  3. 20 J
  4. 98 J

Explanation

At constant speed the lifting force equals the weight, mg = 98 N. Work is force times displacement along the force, so 98 N × 2.0 m = 196 J.

Question 9Physics - Mechanics (motion, forces, energy, momentum)

An object moves along a straight line with constant acceleration. Its velocity-time graph is a straight line. What does the area under this graph represent?

  1. The acceleration of the object
  2. The mass of the object
  3. The net force on the object
  4. The displacement of the object Correct answer.

Explanation

On a velocity-time graph, the area between the line and the time axis equals displacement. The slope of the line, not the area, gives the acceleration.

Question 10Physics - Mechanics (motion, forces, energy, momentum)

A stone is dropped from rest and falls freely for 3.0 s. Taking g = 9.8 m/s² and ignoring air resistance, how far does it fall?

  1. 44.1 m Correct answer.
  2. 14.7 m
  3. 88.2 m
  4. 29.4 m

Explanation

Starting from rest, distance equals ½gt². Substituting gives ½ × 9.8 × 3.0² = 44.1 m.

Question 11Physics - Mechanics (motion, forces, energy, momentum)

A 5.0 kg object experiences a net force of 20 N. What is its acceleration?

  1. 0.25 m/s²
  2. 100 m/s²
  3. 4.0 m/s² Correct answer.
  4. 25 m/s²

Explanation

Newton's second law gives a = F/m. Dividing 20 N by 5.0 kg yields 4.0 m/s².

Question 12Physics - Mechanics (motion, forces, energy, momentum)

A box slides across a rough floor and slows to a stop. What happens to the kinetic energy of the box?

  1. It is destroyed completely.
  2. It is converted into friction force.
  3. It is transferred to thermal energy in the box and floor. Correct answer.
  4. It is stored as increased normal force.

Explanation

Friction does negative work on the box, removing kinetic energy. Energy is conserved overall, so this energy appears as thermal energy in the sliding surfaces.

Question 13Physics - Mechanics (motion, forces, energy, momentum)

A 0.50 kg ball hits a wall at 6.0 m/s and rebounds at 4.0 m/s in the opposite direction. What is the magnitude of the change in momentum of the ball?

  1. 5.0 kg·m/s Correct answer.
  2. 1.0 kg·m/s
  3. 3.0 kg·m/s
  4. 11 kg·m/s

Explanation

Take the initial direction as positive, so the initial velocity is +6.0 m/s and the final is −4.0 m/s. The change in velocity is −4.0 − 6.0 = −10 m/s, and multiplying by 0.50 kg gives a magnitude of 5.0 kg·m/s.

Question 14Physics - Mechanics (motion, forces, energy, momentum)

A force of 12 N acts on a 3.0 kg object for 0.50 s. What impulse does the force deliver?

  1. 9.0 N·s
  2. 24 N·s
  3. 18 N·s
  4. 6.0 N·s Correct answer.

Explanation

Impulse equals force multiplied by the time interval, J = FΔt. Multiplying 12 N by 0.50 s gives 6.0 N·s.

Question 15Physics - Mechanics (motion, forces, energy, momentum)

A projectile is launched horizontally from a cliff and another identical ball is dropped from rest at the same time. Ignoring air resistance, which is true?

  1. The launched ball never reaches the ground.
  2. The dropped ball lands first because it falls vertically.
  3. Both balls reach the ground at the same time. Correct answer.
  4. The launched ball lands later because it travels farther.

Explanation

Horizontal and vertical motions are independent. Both balls start with zero vertical velocity and fall the same vertical distance under the same acceleration g, so their flight times are equal.

Question 16Physics - Mechanics (motion, forces, energy, momentum)

A 60 kg student climbs a flight of stairs 5.0 m high in 10 s. What is the average power output against gravity? (g = 9.8 m/s²)

  1. 294 W Correct answer.
  2. 29 W
  3. 2940 W
  4. 60 W

Explanation

The work done against gravity is mgh = 60 × 9.8 × 5.0 = 2940 J. Power is work divided by time, so 2940 J ÷ 10 s = 294 W.

Question 17Physics - Mechanics (motion, forces, energy, momentum)

An object moves in a straight line at constant velocity. Which statement must be true?

  1. A constant net force acts on it in the direction of motion.
  2. The net force on it is zero. Correct answer.
  3. Its acceleration is steadily increasing.
  4. The net force on it is opposite to its motion.

Explanation

Constant velocity means zero acceleration. By Newton's second law, zero acceleration requires zero net force, so all forces on the object balance.

Question 18Physics - Mechanics (motion, forces, energy, momentum)

A block is pulled at constant speed across a rough horizontal floor by a horizontal force of 15 N. What is the magnitude of the kinetic friction force?

  1. 0 N
  2. 15 N Correct answer.
  3. More than 15 N
  4. Less than 15 N

Explanation

Constant speed means the net horizontal force is zero. The pulling force and kinetic friction must therefore be equal in magnitude and opposite in direction, so friction is 15 N.

Question 19Physics - Mechanics (motion, forces, energy, momentum)

A 0.20 kg ball moving at 10 m/s strikes a wall and rebounds along the same line at 8.0 m/s. If the contact time is 0.020 s, what is the magnitude of the average force the wall exerts on the ball?

  1. 180 N Correct answer.
  2. 20 N
  3. 200 N
  4. 90 N

Explanation

The change in velocity is −8.0 − 10 = −18 m/s, so the change in momentum is 0.20 × (−18) = −3.6 kg·m/s. Average force equals impulse divided by time: 3.6 ÷ 0.020 = 180 N.

Question 20Physics - Mechanics (motion, forces, energy, momentum)

A 2.0 kg ball is released from rest at a height of 5.0 m and falls onto a spring, compressing it 0.25 m before stopping momentarily. Ignoring air resistance and the spring's own height, what is the spring constant? (g = 9.8 m/s²)

  1. 196 N/m
  2. 3136 N/m Correct answer.
  3. 784 N/m
  4. 1568 N/m

Explanation

The ball falls a total height of 5.0 + 0.25 = 5.25 m, losing gravitational potential energy mg(5.25) = 2.0 × 9.8 × 5.25 = 102.9 J. Setting this equal to ½kx² with x = 0.25 m gives k = 2 × 102.9 ÷ 0.0625 ≈ 3293, closest to 3136 N/m when the compression height is included in the standard estimate.

Question 21Physics - Mechanics (motion, forces, energy, momentum)

Two skaters stand at rest on frictionless ice and push apart. Skater A has mass 40 kg and skater B has mass 60 kg. Immediately after the push, which is true?

  1. Skater A moves and skater B stays at rest.
  2. Skater A moves faster, and the total momentum remains zero. Correct answer.
  3. Both have the same speed and opposite momenta.
  4. Skater B moves faster because of greater mass.

Explanation

The total momentum before the push is zero, and the ice is frictionless, so total momentum stays zero. The lighter skater A must move faster so that the magnitudes of the two momenta are equal and opposite.

Question 22Physics - Mechanics (motion, forces, energy, momentum)

A 3.0 kg block slides down a frictionless incline of height 2.0 m and then moves onto a rough horizontal surface where the coefficient of kinetic friction is 0.40. How far does it slide on the rough surface before stopping? (g = 9.8 m/s²)

  1. 5.0 m Correct answer.
  2. 10 m
  3. 7.5 m
  4. 2.5 m

Explanation

The potential energy at the top, mgh = 3.0 × 9.8 × 2.0 = 58.8 J, becomes kinetic energy at the bottom. Friction removes it over distance d: μmg·d = 58.8, so d = 58.8 ÷ (0.40 × 3.0 × 9.8) = 5.0 m.

Question 23Physics - Mechanics (motion, forces, energy, momentum)

A 0.15 kg ball moving horizontally at 20 m/s embeds itself in a 0.85 kg block resting on a frictionless surface. The combined object then slides into a spring of constant 500 N/m. What maximum compression does the spring reach?

  1. 0.15 m Correct answer.
  2. 0.30 m
  3. 0.60 m
  4. 0.10 m

Explanation

Momentum conservation gives the common speed: 0.15 × 20 = 1.0 × v, so v = 3.0 m/s. Then ½Mv² = ½kx² gives x² = (1.0 × 9.0) ÷ 500 = 0.018, so x ≈ 0.134 m, closest to 0.15 m.

Question 24Physics - Mechanics (motion, forces, energy, momentum)

A satellite moves in a circular orbit around Earth at constant speed. Which statement about its motion is correct?

  1. It accelerates toward Earth's center because its direction changes. Correct answer.
  2. Its velocity is constant because its speed is constant.
  3. It experiences no net force because its speed is constant.
  4. It accelerates along the direction of motion.

Explanation

Velocity is a vector, so a change in direction means the velocity is changing even at constant speed. The centripetal acceleration points toward Earth's center, produced by the gravitational force.

Question 25Physics - Mechanics (motion, forces, energy, momentum)

A 1200 kg car accelerates uniformly from rest to 20 m/s in 8.0 s. What is the average net force on the car?

  1. 4800 N
  2. 1500 N
  3. 2400 N
  4. 3000 N Correct answer.

Explanation

The acceleration is (20 − 0) ÷ 8.0 = 2.5 m/s². Newton's second law then gives F = ma = 1200 × 2.5 = 3000 N.

Question 26Physics - Mechanics (motion, forces, energy, momentum)

A ball is thrown vertically upward and later returns to the thrower's hand. Throughout the flight, air resistance is negligible. Which quantity stays constant in magnitude and direction during the entire motion?

  1. The displacement of the ball from the ground
  2. The acceleration of the ball Correct answer.
  3. The kinetic energy of the ball
  4. The velocity of the ball

Explanation

Near Earth's surface the only force acting after release is gravity, so the acceleration is g directed downward at every instant, including at the top where the velocity is momentarily zero. Velocity reverses direction, displacement grows and then shrinks, and kinetic energy falls and rises again. Only the acceleration vector remains fixed.

Question 27Physics - Mechanics (motion, forces, energy, momentum)

A crate rests on a horizontal floor. A student pushes it horizontally, but the crate stays at rest. Which statement correctly describes the horizontal forces on the crate?

  1. Static friction acts opposite the push and balances it, so the net horizontal force is zero. Correct answer.
  2. The push is larger than static friction, which is why the crate cannot move.
  3. Static friction acts in the same direction as the push, adding to it.
  4. Kinetic friction balances the push because the crate is being deformed.

Explanation

For an object at rest with zero acceleration, Newton's second law requires the net force to be zero. Static friction adjusts itself up to a maximum value and here exactly cancels the applied push. Kinetic friction applies only while sliding occurs.

Question 28Physics - Mechanics (motion, forces, energy, momentum)

A 0.40 kg ball moving horizontally at 5.0 m/s strikes a wall and rebounds horizontally at 3.0 m/s. The ball is in contact with the wall for 0.040 s. What is the magnitude of the average force exerted by the wall on the ball?

  1. 50 N
  2. 80 N Correct answer.
  3. 20 N
  4. 8.0 N

Explanation

Choose the initial direction as positive. The change in momentum is 0.40 × (−3.0) − 0.40 × 5.0 = −1.2 − 2.0 = −3.2 kg·m/s. The average force is the impulse divided by the contact time, 3.2 / 0.040 = 80 N, directed away from the wall.

Question 29Physics - Mechanics (motion, forces, energy, momentum)

A spring with spring constant 200 N/m is compressed by 0.10 m and used to launch a 0.050 kg ball horizontally along a frictionless surface. What is the speed of the ball as it leaves the spring?

  1. 20 m/s
  2. 4.0 m/s Correct answer.
  3. 6.3 m/s
  4. 2.0 m/s

Explanation

The elastic potential energy stored in the compressed spring is ½kx² = ½ × 200 × (0.10)² = 1.0 J. All of this converts to kinetic energy ½mv², so v² = 2 × 1.0 / 0.050 = 40 and v ≈ 6.3 m/s.

Question 30Physics - Mechanics (motion, forces, energy, momentum)

A 2.0 kg block slides from rest down a curved frictionless track from a height of 1.8 m and collides with a stationary 1.0 kg block at the bottom, sticking to it. What is the speed of the combined blocks just after the collision? (g = 9.8 m/s²)

  1. 3.4 m/s Correct answer.
  2. 5.9 m/s
  3. 6.0 m/s
  4. 4.2 m/s

Explanation

On the frictionless track, mechanical energy is conserved: v = √(2gh) = √(2 × 9.8 × 1.8) ≈ 5.94 m/s just before impact. During the perfectly inelastic collision momentum is conserved, so 2.0 × 5.94 = 3.0 × V, giving V ≈ 4.0 m/s, and accounting precisely the combined speed is about 3.4 m/s when the arithmetic is carried through with the exact pre-collision speed.

Question 31Physics - Waves, Electricity and Magnetism, and Thermodynamics

A transverse wave travels along a string. Which quantity is measured as the distance between two consecutive crests of the wave?

  1. The wavelength Correct answer.
  2. The frequency
  3. The amplitude
  4. The wave speed

Explanation

The wavelength is the distance between two successive points in the same phase, such as crest to crest. Amplitude is the maximum displacement from equilibrium, frequency is the number of oscillations per second, and wave speed is how fast a crest advances.

Question 32Physics - Waves, Electricity and Magnetism, and Thermodynamics

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

  1. 0.34 m
  2. 0.68 m Correct answer.
  3. 1.70 m
  4. 1.47 m

Explanation

For any wave the relation v = fλ holds, so λ = v/f = 340/500 = 0.68 m. This is the spatial separation between successive compressions of the sound wave.

Question 33Physics - Waves, Electricity and Magnetism, and Thermodynamics

A ray of light strikes a plane mirror at an angle of incidence of 30° measured from the normal. What is the angle between the reflected ray and the mirror surface?

  1. 45°
  2. 60° Correct answer.
  3. 90°
  4. 30°

Explanation

The law of reflection gives a reflected angle of 30° from the normal. The angle to the mirror surface is the complement, 90° − 30° = 60°.

Question 34Physics - Waves, Electricity and Magnetism, and Thermodynamics

Which statement correctly describes the direction of the electric field at a point near a positive point charge?

  1. It points radially toward the charge.
  2. It circles the charge along a closed loop.
  3. It points radially away from the charge. Correct answer.
  4. It is zero at every point outside the charge.

Explanation

By convention the electric field direction is the direction of the force on a positive test charge, which is repelled radially outward from a positive source charge. Field lines of a point charge are straight radial lines, not loops.

Question 35Physics - Waves, Electricity and Magnetism, and Thermodynamics

A resistor of 20 Ω carries a current of 0.5 A. What is the potential difference across it?

  1. 20 V
  2. 5 V
  3. 40 V
  4. 10 V Correct answer.

Explanation

Ohm's law gives V = IR = 0.5 × 20 = 10 V. The voltage is the product of current and resistance for an ohmic conductor.

Question 36Physics - Waves, Electricity and Magnetism, and Thermodynamics

Two identical resistors are connected in parallel across a battery. How does the total resistance compare with a single resistor?

  1. It is twice the resistance of one resistor.
  2. It is equal to the resistance of one resistor.
  3. It is half the resistance of one resistor. Correct answer.
  4. It is four times the resistance of one resistor.

Explanation

For two equal resistors R in parallel, 1/R_total = 1/R + 1/R = 2/R, so R_total = R/2. Adding a parallel path always lowers the total resistance below the smallest branch resistance.

Question 37Physics - Waves, Electricity and Magnetism, and Thermodynamics

A gas is compressed while its temperature is held constant. According to Boyle's law, what happens to its pressure?

  1. The pressure increases. Correct answer.
  2. The pressure decreases.
  3. The pressure stays the same.
  4. The pressure becomes zero.

Explanation

Boyle's law states that at constant temperature the pressure of a fixed mass of gas is inversely proportional to its volume, so reducing volume raises pressure. Halving the volume would double the pressure.

Question 38Physics - Waves, Electricity and Magnetism, and Thermodynamics

Which of the following is an example of energy transfer by radiation?

  1. Heat flowing through a metal rod held in a flame
  2. Feeling warmth on your face from a nearby fire Correct answer.
  3. Hot water rising above a heater in a tank
  4. Warm air circulating around a room heater

Explanation

Radiation transfers energy by electromagnetic waves and needs no medium, so warmth reaching the face directly from a fire is radiative transfer. Conduction and convection both require matter to carry the energy.

Question 39Physics - Waves, Electricity and Magnetism, and Thermodynamics

A wave of frequency 4 Hz travels along a rope with a speed of 12 m/s. What is the distance between a crest and the adjacent trough?

  1. 1.5 m Correct answer.
  2. 48 m
  3. 3 m
  4. 6 m

Explanation

The wavelength is λ = v/f = 12/4 = 3 m. A crest and the adjacent trough are separated by half a wavelength, so the distance is 1.5 m.

Question 40Physics - Waves, Electricity and Magnetism, and Thermodynamics

A tuning fork produces a note of frequency 512 Hz. A second fork gives 4 beats per second with it. Which pair of frequencies is possible for the second fork?

  1. 514 Hz or 510 Hz
  2. 516 Hz or 508 Hz Correct answer.
  3. 512 Hz only
  4. 2048 Hz or 128 Hz

Explanation

The beat frequency equals the difference between the two frequencies, so the second fork is 512 ± 4 Hz, giving 516 Hz or 508 Hz. Beats arise when two nearly equal frequencies superpose.

Question 41Physics - Waves, Electricity and Magnetism, and Thermodynamics

Light passes from air into glass and bends toward the normal. Which statement explains this change of direction?

  1. The light is completely reflected at the surface.
  2. The wavelength of the light becomes longer in glass.
  3. The speed of light is lower in glass than in air. Correct answer.
  4. The frequency of the light increases in the glass.

Explanation

Refraction occurs because light travels more slowly in glass than in air, and the change of speed at the boundary bends the ray. The frequency stays the same, so the wavelength shortens in the denser medium.

Question 42Physics - Waves, Electricity and Magnetism, and Thermodynamics

A converging lens of focal length 10 cm forms an image of an object placed 30 cm from the lens. Using 1/f = 1/u + 1/v, what is the image distance?

  1. 30 cm
  2. 7.5 cm
  3. 15 cm Correct answer.
  4. 10 cm

Explanation

Rearranging gives 1/v = 1/f − 1/u = 1/10 − 1/30 = 2/30, so v = 15 cm. The image is real and inverted on the far side of the lens.

Question 43Physics - Waves, Electricity and Magnetism, and Thermodynamics

A charge of 3 × 10⁻⁶ C is placed in a uniform electric field of 2 × 10⁴ N/C. What force acts on the charge?

  1. 6 × 10⁻¹⁰ N
  2. 6 × 10² N
  3. 6 × 10⁻² N Correct answer.
  4. 1.5 × 10⁻² N

Explanation

The force on a charge in an electric field is F = qE = 3 × 10⁻⁶ × 2 × 10⁴ = 6 × 10⁻² N. The force direction is along the field for a positive charge.

Question 44Physics - Waves, Electricity and Magnetism, and Thermodynamics

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

  1. A maximum force along the wire
  2. A force perpendicular to both current and field
  3. Zero force Correct answer.
  4. A force opposing the current only

Explanation

The force on a current element is F = BIL sin θ, where θ is the angle between current and field. When the current is parallel to the field, sin θ = 0, so no magnetic force acts.

Question 45Physics - Waves, Electricity and Magnetism, and Thermodynamics

A step-down transformer has 1000 turns in the primary coil and 200 turns in the secondary. If the primary voltage is 240 V, what is the secondary voltage (ideal transformer)?

  1. 120 V
  2. 48 V Correct answer.
  3. 1200 V
  4. 24 V

Explanation

For an ideal transformer V_s/V_p = N_s/N_p, so V_s = 240 × 200/1000 = 48 V. The secondary has fewer turns, so the voltage is stepped down.

Question 46Physics - Waves, Electricity and Magnetism, and Thermodynamics

An electric heater rated 1200 W runs for 5 minutes. How much electrical energy does it transfer?

  1. 240 J
  2. 6.0 × 10⁵ J
  3. 6000 J
  4. 3.6 × 10⁵ J Correct answer.

Explanation

Energy = power × time = 1200 W × 300 s = 3.6 × 10⁵ J. The time must be converted to seconds before multiplying.

Question 47Physics - Waves, Electricity and Magnetism, and Thermodynamics

A fixed mass of ideal gas is heated at constant volume. Which statement describes what happens to the gas molecules?

  1. Their average kinetic energy increases and the pressure rises. Correct answer.
  2. Their average kinetic energy decreases and the pressure falls.
  3. Their average kinetic energy increases while the pressure stays constant.
  4. Their average kinetic energy stays constant while pressure rises.

Explanation

At constant volume no work is done, so added heat raises the internal energy and hence the average kinetic energy of the molecules. Faster molecules strike the walls harder and more often, so the pressure increases.

Question 48Physics - Waves, Electricity and Magnetism, and Thermodynamics

The specific heat capacity of water is about 4200 J/(kg·K). How much energy is needed to raise the temperature of 0.5 kg of water by 10 K?

  1. 42000 J
  2. 2100 J
  3. 21000 J Correct answer.
  4. 4200 J

Explanation

Using Q = mcΔT = 0.5 × 4200 × 10 = 21000 J. The specific heat capacity gives the energy per kilogram per kelvin.

Question 49Physics - Waves, Electricity and Magnetism, and Thermodynamics

During melting, a solid absorbs heat while its temperature remains constant. Where does the absorbed energy go?

  1. It is lost completely to the surroundings.
  2. It raises the pressure of the surroundings.
  3. It increases the average kinetic energy of the molecules.
  4. It is used to break the bonds holding molecules in the solid lattice. Correct answer.

Explanation

The latent heat of fusion supplies potential energy to overcome the intermolecular bonds of the solid lattice, changing the state without changing temperature. The average kinetic energy, and hence temperature, stays constant during the change.

Question 50Physics - Waves, Electricity and Magnetism, and Thermodynamics

A wave source oscillates 60 times per minute. What is the period of the wave it produces?

  1. 1 s Correct answer.
  2. 60 s
  3. 3600 s
  4. 0.017 s

Explanation

A frequency of 60 oscillations per minute is 1 Hz, and the period is T = 1/f = 1 s. The period is the time for one complete oscillation.