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Ehime Entrance Science study materials
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Ehime Entrance Science practice questions

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Question 1Physics

A ball is thrown vertically upward from the ground with an initial speed of 19.6 m/s. Taking g = 9.8 m/s² and neglecting air resistance, how long does the ball take to return to the ground?

  1. 1.0 s
  2. 2.0 s
  3. 9.8 s
  4. 4.0 s Correct answer.

Explanation

For vertical motion under constant acceleration, the time to rise to the highest point equals the time to fall back, and the total flight time is 2v₀/g. Substituting v₀ = 19.6 m/s and g = 9.8 m/s² gives 2 × 19.6 ÷ 9.8 = 4.0 s. The upward and downward legs are symmetric because the acceleration is constant.

Question 2Physics

A car travels 60 m east and then 80 m north along straight roads. What is the magnitude of its resultant displacement from the starting point?

  1. 140 m
  2. 20 m
  3. 100 m Correct answer.
  4. 70 m

Explanation

The two displacements are perpendicular, so the resultant magnitude is found with the Pythagorean theorem: √(60² + 80²) = √(3600 + 6400) = √10000 = 100 m. Adding the magnitudes directly would ignore the change in direction.

Question 3Physics

Which statement correctly describes Newton's third law of motion as applied to a book resting on a table?

  1. The normal force from the table on the book and the gravitational force on the book are an action–reaction pair.
  2. The weight of the book and the weight of the table are an action–reaction pair.
  3. The normal force from the table on the book and the downward push of the book on the table are an action–reaction pair. Correct answer.
  4. The book stays at rest because no forces act on it.

Explanation

An action–reaction pair consists of two forces of the same type, equal in magnitude and opposite in direction, acting on two different bodies. The table pushes up on the book while the book pushes down on the table with an equal contact (normal) force. The book's weight and the normal force balance the book but act on the same body, so they are not a third-law pair.

Question 4Physics

A 2.0 kg object experiences a net force of 6.0 N. What is the magnitude of its acceleration?

  1. 0.33 m/s²
  2. 8.0 m/s²
  3. 3.0 m/s² Correct answer.
  4. 12 m/s²

Explanation

Newton's second law gives a = F/m. Dividing 6.0 N by 2.0 kg yields 3.0 m/s², and the direction of the acceleration matches the net force.

Question 5Physics

A box of mass 5.0 kg is pulled along a horizontal floor by a horizontal force of 20 N against a constant kinetic friction force of 5.0 N. What is the acceleration of the box?

  1. 3.0 m/s² Correct answer.
  2. 1.0 m/s²
  3. 4.0 m/s²
  4. 5.0 m/s²

Explanation

The net horizontal force is the applied force minus friction: 20 N − 5.0 N = 15 N. Dividing by the mass gives a = 15 ÷ 5.0 = 3.0 m/s². Friction must be subtracted because it opposes the motion.

Question 6Physics

A 0.50 kg ball moving at 4.0 m/s strikes a wall and rebounds along the same line at 3.0 m/s. Taking the initial direction as positive, what is the change in momentum of the ball?

  1. +3.5 kg·m/s
  2. −0.50 kg·m/s
  3. −3.5 kg·m/s Correct answer.
  4. +0.50 kg·m/s

Explanation

Momentum is a vector, so the rebound velocity is negative. Initial momentum is 0.50 × 4.0 = +2.0 kg·m/s and final momentum is 0.50 × (−3.0) = −1.5 kg·m/s. The change is final minus initial: −1.5 − 2.0 = −3.5 kg·m/s.

Question 7Physics

Two identical carts on a frictionless track collide and stick together. Cart A moves at 3.0 m/s and cart B is at rest. If each cart has mass 1.0 kg, what is the speed of the combined carts after the collision?

  1. 6.0 m/s
  2. 1.5 m/s Correct answer.
  3. 0 m/s
  4. 3.0 m/s

Explanation

With no external horizontal force, total momentum is conserved. Before the collision p = 1.0 × 3.0 = 3.0 kg·m/s; after sticking, the combined mass is 2.0 kg, so v = 3.0 ÷ 2.0 = 1.5 m/s. Kinetic energy is not conserved in a perfectly inelastic collision.

Question 8Physics

A force of 10 N is applied to a lever at a distance of 0.50 m from the pivot. What is the torque about the pivot when the force acts perpendicular to the lever arm?

  1. 5.0 N·m Correct answer.
  2. 20 N·m
  3. 0.050 N·m
  4. 10 N·m

Explanation

Torque equals force times the perpendicular distance from the pivot: τ = F × r = 10 × 0.50 = 5.0 N·m. When the force is perpendicular to the lever arm, the full force contributes to the torque.

Question 9Physics

A uniform metre rule is pivoted at its centre and balances horizontally. A 2.0 N weight hangs 20 cm to the left of the pivot. Where must a 4.0 N weight be hung to keep the rule balanced?

  1. 40 cm to the right of the pivot
  2. 5.0 cm to the right of the pivot
  3. 10 cm to the right of the pivot Correct answer.
  4. 20 cm to the right of the pivot

Explanation

For rotational equilibrium the clockwise and anticlockwise torques must be equal. The left torque is 2.0 N × 20 cm = 40 N·cm, so the right distance is 40 ÷ 4.0 = 10 cm. The larger weight must sit closer to the pivot.

Question 10Physics

A crate of weight 200 N is lifted vertically at constant speed through a height of 3.0 m. How much work is done against gravity?

  1. 600 J Correct answer.
  2. 0 J
  3. 67 J
  4. 200 J

Explanation

Work done against gravity equals weight times vertical height: W = 200 N × 3.0 m = 600 J. Lifting at constant speed means the applied force equals the weight, so the full weight contributes.

Question 11Physics

A machine raises a 50 N load through 2.0 m in 4.0 s. What is the average useful power output of the machine?

  1. 100 W
  2. 12.5 W
  3. 25 W Correct answer.
  4. 400 W

Explanation

Power is work done per unit time. The work is 50 N × 2.0 m = 100 J, and dividing by 4.0 s gives 25 W. The result is a rate, so the time interval must appear in the calculation.

Question 12Physics

A ball of mass 0.20 kg is held 5.0 m above the ground. Taking g = 9.8 m/s², what is its gravitational potential energy relative to the ground?

  1. 0.98 J
  2. 9.8 J Correct answer.
  3. 49 J
  4. 1.0 J

Explanation

Gravitational potential energy is mgh = 0.20 × 9.8 × 5.0 = 9.8 J. The reference level is the ground, so the height used is 5.0 m.

Question 13Physics

A pendulum bob is released from rest at a height of 0.80 m above its lowest point. Neglecting air resistance, what is its speed at the lowest point? Take g = 9.8 m/s².

  1. 2.0 m/s
  2. 7.8 m/s
  3. 3.9 m/s Correct answer.
  4. 1.6 m/s

Explanation

Mechanical energy is conserved, so mgh = ½mv². Cancelling mass gives v = √(2gh) = √(2 × 9.8 × 0.80) = √15.68 ≈ 3.9 m/s. The mass of the bob does not affect the result.

Question 14Physics

A spring obeys Hooke's law with a spring constant of 200 N/m. What force is needed to stretch it by 0.10 m from its natural length?

  1. 0.0005 N
  2. 2.0 N
  3. 2000 N
  4. 20 N Correct answer.

Explanation

Hooke's law states F = kx, so F = 200 × 0.10 = 20 N. The extension must be measured from the natural length of the spring.

Question 15Physics

A wave has a frequency of 50 Hz and a wavelength of 4.0 m. What is its speed?

  1. 0.080 m/s
  2. 54 m/s
  3. 200 m/s Correct answer.
  4. 12.5 m/s

Explanation

The wave equation relates speed, frequency, and wavelength: v = fλ. Multiplying 50 Hz by 4.0 m gives 200 m/s. Frequency is the number of oscillations per second and wavelength the distance per oscillation.

Question 16Physics

A sound wave travels from air into water. Which quantity remains unchanged as the wave crosses the boundary?

  1. Frequency Correct answer.
  2. Wavelength
  3. Direction of travel
  4. Speed

Explanation

Frequency is set by the source and is unchanged when a wave enters a new medium. Speed changes with the medium, and because v = fλ, the wavelength must change in proportion to the speed. Refraction may also bend the direction of travel.

Question 17Physics

Light of wavelength 600 nm passes through a double slit and forms an interference pattern on a screen. If the slit separation is doubled while everything else is unchanged, what happens to the fringe spacing?

  1. It stays the same.
  2. It doubles.
  3. It halves. Correct answer.
  4. It becomes four times larger.

Explanation

For double-slit interference the fringe spacing is Δy = λL/d, where d is the slit separation. Since Δy is inversely proportional to d, doubling d halves the spacing. Wavelength and screen distance are unchanged.

Question 18Physics

An object is placed 30 cm in front of a converging lens of focal length 10 cm. Where is the image formed?

  1. 10 cm behind the lens
  2. 30 cm in front of the lens
  3. 15 cm behind the lens Correct answer.
  4. 20 cm behind the lens

Explanation

The thin-lens equation is 1/f = 1/u + 1/v with u = 30 cm and f = 10 cm. So 1/v = 1/10 − 1/30 = 2/30, giving v = 15 cm. A positive v means a real image on the far side of the lens.

Question 19Physics

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 incident ray and the reflected ray?

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

Explanation

The law of reflection states that the angle of reflection equals the angle of incidence, both measured from the normal. The angle between the two rays is therefore 30° + 30° = 60°. The angles are measured from the normal, not from the mirror surface.

Question 20Physics

A current of 2.0 A flows through a resistor of 15 Ω. What is the potential difference across the resistor?

  1. 0.13 V
  2. 30 V Correct answer.
  3. 17 V
  4. 7.5 V

Explanation

Ohm's law gives V = IR, so V = 2.0 × 15 = 30 V. Current and resistance are multiplied to find the potential difference.

Question 21Physics

Two resistors of 6.0 Ω and 3.0 Ω are connected in parallel. What is the equivalent resistance of the combination?

  1. 9.0 Ω
  2. 2.0 Ω Correct answer.
  3. 18 Ω
  4. 4.5 Ω

Explanation

For parallel resistors, 1/R = 1/6.0 + 1/3.0 = 1/6.0 + 2/6.0 = 3/6.0, so R = 2.0 Ω. The equivalent resistance is always smaller than the smallest individual resistance.

Question 22Physics

An electric heater draws 5.0 A from a 100 V supply. What is its power consumption?

  1. 20 W
  2. 500 W Correct answer.
  3. 0.050 W
  4. 105 W

Explanation

Electrical power is P = VI, so P = 100 × 5.0 = 500 W. Multiplying potential difference by current gives the rate at which electrical energy is converted.

Question 23Physics

A charge of 0.020 C flows past a point in a wire in 4.0 s. What is the current in the wire?

  1. 0.080 A
  2. 0.0050 A Correct answer.
  3. 4.0 A
  4. 80 A

Explanation

Current is the rate of flow of charge: I = Q/t. Dividing 0.020 C by 4.0 s gives 0.0050 A. The result is a rate, so charge must be divided by time.

Question 24Physics

A straight wire carries a current upward through a region where the magnetic field points horizontally to the right. In which direction does the magnetic force on the wire act?

  1. To the right, parallel to the field
  2. Out of the page
  3. Upward, parallel to the current
  4. Into the page Correct answer.

Explanation

The magnetic force on a current-carrying wire is given by F = BIL sinθ and is perpendicular to both the current and the field. Using the left-hand (or right-hand) rule with current upward and field to the right gives a force directed into the page. A force parallel to either vector would violate this perpendicularity.

Question 25Physics

A step-down transformer has 1000 turns on its primary coil and 200 turns on its secondary coil. If the primary voltage is 240 V, what is the secondary voltage, assuming an ideal transformer?

  1. 24 V
  2. 240 V
  3. 1200 V
  4. 48 V Correct answer.

Explanation

For an ideal transformer, the voltage ratio equals the turns ratio: V₂/V₁ = N₂/N₁. Thus V₂ = 240 × 200/1000 = 48 V. A step-down transformer has fewer secondary turns and lowers the voltage.

Question 26Physics

A car travels along a straight road at a constant velocity of 12 m/s for 5.0 s, then accelerates uniformly to 20 m/s over the next 4.0 s. What is the total distance travelled during the 9.0 s?

  1. 124 m
  2. 108 m
  3. 92 m Correct answer.
  4. 140 m

Explanation

During the constant-velocity stage the distance is 12 × 5.0 = 60 m. During the acceleration stage the average velocity is (12 + 20)/2 = 16 m/s, giving 16 × 4.0 = 64 m. Adding the two stages gives 60 + 64 = 124 m.

Question 27Physics

A stone is dropped from rest from a cliff and takes 3.0 s to reach the ground. Taking g = 9.8 m/s² and ignoring air resistance, how high is the cliff?

  1. 44 m Correct answer.
  2. 29 m
  3. 59 m
  4. 88 m

Explanation

For free fall from rest, height = ½gt² = ½ × 9.8 × 3.0² = 44.1 m, which rounds to 44 m. The velocity at impact, 29 m/s, is not the height.

Question 28Physics

A projectile is launched at 20 m/s at 30° above the horizontal on level ground. Taking g = 9.8 m/s², what is the maximum height reached?

  1. 2.0 m
  2. 5.1 m Correct answer.
  3. 20 m
  4. 10 m

Explanation

The vertical component of velocity is 20 sin 30° = 10 m/s. Maximum height is v_y²/(2g) = 100/19.6 ≈ 5.1 m.

Question 29Physics

An object moves in a circle of radius 2.0 m at a constant speed of 6.0 m/s. What is the magnitude of its centripetal acceleration?

  1. 12 m/s²
  2. 36 m/s²
  3. 18 m/s² Correct answer.
  4. 3.0 m/s²

Explanation

Centripetal acceleration is a = v²/r = 6.0²/2.0 = 36/2.0 = 18 m/s². It points toward the centre of the circle even though the speed is constant.

Question 30Physics

A block of mass 4.0 kg rests on a horizontal floor. A horizontal force of 14 N is applied, but the block remains stationary. What is the magnitude of the static friction force acting on the block?

  1. 14 N Correct answer.
  2. 0 N
  3. 39 N
  4. 3.5 N

Explanation

Since the block does not move, the net horizontal force is zero, so static friction must exactly balance the applied force: 14 N. Static friction takes whatever value is needed up to its maximum.

Question 31Physics

A person of mass 60 kg stands in a lift. Taking g = 9.8 m/s², what is the magnitude of the normal force from the floor when the lift accelerates upward at 2.0 m/s²?

  1. 470 N
  2. 710 N Correct answer.
  3. 590 N
  4. 1200 N

Explanation

Newton's second law upward gives N − mg = ma, so N = m(g + a) = 60 × (9.8 + 2.0) = 60 × 11.8 = 708 N ≈ 710 N. The apparent weight exceeds the true weight.

Question 32Physics

A gas in a cylinder is compressed slowly while its temperature is kept constant. Which statement about the gas is correct?

  1. The pressure increases because the average kinetic energy of the molecules rises.
  2. The pressure increases because the molecules strike the walls more frequently per unit area. Correct answer.
  3. The pressure stays the same because the temperature is unchanged.
  4. The pressure decreases because the molecules move more slowly.

Explanation

At constant temperature the average molecular kinetic energy is fixed, but the molecules are confined to a smaller volume, so they hit unit area of the wall more often. By Boyle's law, pV is constant, so reducing V raises p.

Question 33Physics

A sealed rigid container holds a fixed mass of gas. The gas is heated so that its absolute temperature doubles. What happens to the pressure?

  1. It stays the same.
  2. It doubles. Correct answer.
  3. It quadruples.
  4. It halves.

Explanation

For a fixed mass at constant volume, pressure is directly proportional to absolute temperature (p/T = constant). Doubling the absolute temperature therefore doubles the pressure.

Question 34Physics

A metal rod expands when heated. Which statement best explains this at the molecular level?

  1. The atoms themselves become larger because each atom expands.
  2. The number of atoms in the rod increases with temperature.
  3. The average separation of the atoms increases as they vibrate with greater amplitude. Correct answer.
  4. The mass of each atom increases with temperature.

Explanation

Thermal expansion arises because atoms vibrate about equilibrium positions with greater amplitude at higher temperature. Because the interatomic potential is asymmetric, the mean separation increases, so the whole rod lengthens.

Question 35Physics

An ideal gas absorbs 500 J of heat and does 200 J of work on its surroundings. What is the change in its internal energy?

  1. −700 J
  2. 700 J
  3. 300 J Correct answer.
  4. −300 J

Explanation

By the first law of thermodynamics, ΔU = Q − W, where W is work done by the gas. Here ΔU = 500 − 200 = 300 J, so the internal energy rises by 300 J.

Question 36Physics

Two point charges are separated by a distance r in vacuum. If the distance between them is doubled while the charges are unchanged, the magnitude of the electrostatic force becomes

  1. one half of its original value
  2. one quarter of its original value Correct answer.
  3. four times its original value
  4. twice its original value

Explanation

Coulomb's law gives F ∝ 1/r². Doubling r multiplies the force by 1/2² = 1/4, so the force falls to one quarter of its original magnitude.

Question 37Physics

A 12 V battery is connected to two resistors of 4.0 Ω and 8.0 Ω in series. What is the potential difference across the 8.0 Ω resistor?

  1. 6.0 V
  2. 8.0 V Correct answer.
  3. 12 V
  4. 4.0 V

Explanation

The series resistance is 12 Ω, so the current is 12/12 = 1.0 A. The voltage across the 8.0 Ω resistor is IR = 1.0 × 8.0 = 8.0 V, in proportion to its resistance.

Question 38Physics

An electric kettle rated 1500 W is used to heat 1.0 kg of water from 20 °C to 100 °C. Taking the specific heat capacity of water as 4200 J/(kg·K) and ignoring losses, how long does it take?

  1. 420 s
  2. 280 s
  3. 224 s Correct answer.
  4. 56 s

Explanation

Energy needed is mcΔT = 1.0 × 4200 × 80 = 336 000 J. Time = energy/power = 336 000/1500 ≈ 224 s, about 3.7 minutes.

Question 39Physics

A positively charged particle enters a uniform magnetic field moving parallel to the field lines. What is the magnetic force on the particle?

  1. Maximum, because the velocity is parallel to the field.
  2. Zero, because the velocity is parallel to the field. Correct answer.
  3. Directed along the velocity.
  4. Directed opposite to the magnetic field.

Explanation

The magnetic force is F = qvB sin θ, where θ is the angle between velocity and field. When the particle moves parallel to the field, θ = 0 and sin θ = 0, so the force is zero.

Question 40Physics

A coil of 200 turns and area 0.010 m² lies in a uniform magnetic field that increases from 0 to 0.50 T in 2.0 s. What is the magnitude of the average induced emf in the coil?

  1. 1.0 V
  2. 0.50 V Correct answer.
  3. 0.25 V
  4. 2.0 V

Explanation

Faraday's law gives emf = N ΔΦ/Δt = N A ΔB/Δt = 200 × 0.010 × (0.50/2.0) = 200 × 0.010 × 0.25 = 0.50 V.

Question 41Physics

A sound source moving toward a stationary observer emits a constant frequency. Which statement describes what the observer hears?

  1. A higher frequency, because the wavefronts are compressed in the direction of motion. Correct answer.
  2. The same frequency, because the source speed does not affect the wave speed.
  3. A lower frequency, because the source is closer to the observer.
  4. A higher speed of sound, because the source adds to the wave speed.

Explanation

In the Doppler effect, motion of the source toward the observer crowds the wavefronts together, shortening the observed wavelength. Since the wave speed in air is unchanged, the observed frequency rises.

Question 42Physics

Unpolarised light of intensity I₀ passes through a single ideal polarising filter. What is the intensity of the transmitted light?

  1. I₀
  2. Zero
  3. I₀/4
  4. I₀/2 Correct answer.

Explanation

Unpolarised light has its electric field randomly oriented, so on average half the intensity passes any single ideal polariser. The transmitted light is plane-polarised with intensity I₀/2.

Question 43Physics

A photon has energy 3.3 × 10⁻¹⁹ J. Taking Planck's constant as 6.6 × 10⁻³⁴ J·s, what is its frequency?

  1. 5.0 × 10¹⁵ Hz
  2. 2.0 × 10¹⁵ Hz
  3. 5.0 × 10¹⁴ Hz Correct answer.
  4. 2.0 × 10¹⁴ Hz

Explanation

Photon energy is E = hf, so f = E/h = 3.3 × 10⁻¹⁹ / 6.6 × 10⁻³⁴ = 5.0 × 10¹⁴ Hz. This lies in the visible region of the spectrum.

Question 44Physics

In the photoelectric effect, light of a fixed frequency above the threshold shines on a metal surface. If the intensity of the light is increased while the frequency is unchanged, what happens?

  1. The threshold frequency of the metal decreases.
  2. The number of electrons emitted per second increases. Correct answer.
  3. The maximum kinetic energy of the emitted electrons increases.
  4. The stopping potential increases.

Explanation

Intensity sets the number of photons arriving per second, so more electrons are released per second. The maximum kinetic energy depends only on the photon energy and the work function, so it is unchanged.

Question 45Physics

A radioactive source has a half-life of 8.0 days. What fraction of the original nuclei remains after 24 days?

  1. 1/3
  2. 1/6
  3. 1/24
  4. 1/8 Correct answer.

Explanation

24 days is three half-lives (24/8 = 3). After each half-life the number remaining halves, so the fraction is (1/2)³ = 1/8.

Question 46Physics

In a nuclear fission reaction, the total mass of the products is slightly less than the total mass of the reactants. What accounts for the missing mass?

  1. It is converted into energy released in the reaction. Correct answer.
  2. It is converted into neutrons that escape.
  3. It is lost because mass is not conserved in any reaction.
  4. It is converted into the binding energy of the reactants.

Explanation

The mass difference is released as energy according to E = mc². Because c² is very large, a small mass defect corresponds to a substantial energy release.

Question 47Physics

A spring of spring constant 100 N/m is stretched 0.20 m from its natural length. What is the elastic potential energy stored in the spring?

  1. 10 J
  2. 20 J
  3. 2.0 J Correct answer.
  4. 1.0 J

Explanation

Elastic potential energy is ½kx² = ½ × 100 × 0.20² = ½ × 100 × 0.040 = 2.0 J. The linear formula kx would give the force, not the energy.

Question 48Physics

A wave on a string has an amplitude of 2.0 cm and a frequency of 5.0 Hz. What is the period of the wave?

  1. 0.20 s Correct answer.
  2. 0.10 s
  3. 0.50 s
  4. 5.0 s

Explanation

The period is the reciprocal of the frequency: T = 1/f = 1/5.0 = 0.20 s. Amplitude does not affect the period.

Question 49Physics

A converging lens of focal length 15 cm forms a real image of an object placed 45 cm from the lens. What is the magnification?

  1. +0.33
  2. −0.33
  3. +0.50
  4. −0.50 Correct answer.

Explanation

Using 1/f = 1/u + 1/v gives 1/v = 1/15 − 1/45 = 2/45, so v = 22.5 cm. Magnification m = −v/u = −22.5/45 = −0.50, showing a real, inverted, diminished image.

Question 50Physics

An object floats in water with 60% of its volume submerged. What is the density of the object? Take the density of water as 1000 kg/m³.

  1. 1670 kg/m³
  2. 400 kg/m³
  3. 1000 kg/m³
  4. 600 kg/m³ Correct answer.

Explanation

For a floating body, the weight equals the weight of displaced fluid, so the object density equals the fraction submerged times the fluid density: 0.60 × 1000 = 600 kg/m³.