PhysicsLAB: MCAS 2025 Session 2

MCAS Physics Exams
MCAS 2025 Session 2

This page begins with the final questions (18-20) to Session 1. Then it contains all of the questions (22-43) in Session 2.

Reference Sheet for Introductory Physics

Tritium is a form of hydrogen. The diagram shows a model of a tritium nucleus before and after it undergoes a nuclear process. The tritium nucleus is at rest before the nuclear process. The arrows represent the magnitude and direction of the velocity of the particles after the nuclear process.

Which of the following best describes the nuclear process shown in the model?

A The nuclear process is fusion, and energy is released.
B The nuclear process is fusion, and energy is absorbed.
C The nuclear process is beta decay, and energy is released.
D The nuclear process is beta decay, and energy is absorbed.

A musical instrument produces a sound with a frequency of 1318 Hz. The speed of the sound wave is 340 m/s. What is the wavelength of the sound that the instrument produces?

A 0.003 mB 0.258 mC 978.0 mD 1658 m

This question has three parts.

The diagram shows the horizontal forces on a cart. Assume friction is negligible and the cart is initially at rest.

Part A.Identify the direction the cart moves. Explain your reasoning.

Part B. Calculate the cart’s acceleration. Show your calculations and include units in your answer.

Part C. Determine the magnitude and direction of an additional force that will give the cart an acceleration of 1.5 m/s² to the right. Show your calculations and include units in your answer.

This question has four parts. Write your response on the next page. Be sure to label each part of your response.

Two copper objects, X and Y, have different shapes. Each object is heated to 100°C and then placed in its own jar. Each jar contains the same amount of water that is at the same temperature. Object Y cools at a faster rate than object X because object Y has a greater surface area. The graph shows the temperature of each object over time.

Part A. Was the initial water temperature higher than 100°C, between 100°C and 60°C, or lower than 60°C? Explain your reasoning.

Part B. Describe when the copper objects will stop cooling.

Part C. The mass of each copper object is 10 g. Compare the thermal energy lost by the two objects from 0 s to 30 s. Explain your reasoning.

Part D. Describe how the total heat transfer between a 10 g object and the water would be different if the object were made of a metal with a higher specific heat.

A block of ice at –4°C and a cup of 80°C water are placed in a 23°C room. Which statement describes the flow of heat in this situation?

A Heat flows into the ice and into the water.
B Heat flows out of the ice and out of the water.
C Heat flows out of the ice and into the water.
D Heat flows into the ice and out of the water.

A student is 1 m away from two vending machines, R and S, in a school cafeteria. Vending machine R has twice the mass of vending machine S. Which of the following best describes the gravitational forces that the vending machines exert on the student?

A Vending machine R exerts half as much gravitational force on the student as vending machine S does.
B Vending machine R exerts the same amount of gravitational force on the student as vending machine S does.
C Vending machine R exerts twice as much gravitational force on the student as vending machine S does.
D Vending machine R exerts four times as much gravitational force on the student as vending machine S does.

Students are analyzing the results of three investigations as they learn about the wave and particle models of light. The three investigations, X, Y, and Z, are represented in the diagrams.

Part A: In investigation X, light behaves like a

A particle.B wave.

Part B: In investigation Y, light behaves like a

A particle.B wave.

Part C: In investigation Z, light behaves like a

A particle.B wave.

The graph shows the positions of two carts, cart X and cart Y, before and after they collided on a track. Assume friction was negligible and that the total momentum of the two-cart system was conserved during the collision.

Part A: Which cart was at rest before the collision?

Part B: After the collision, the carts

A were not moving.B moved in the same direction.C moved in opposite directions.

Part C: Which of the following best describes the two-cart system?

A The net force on the system was zero during the collision.
B The momentum of the system decreased during the collision.
C The velocity of the system was conserved during the collision.
D The kinetic energy of the system increased during the collision

A 30 kg crate is being lifted upward with a rope. The rope applies a constant upward force of 360 N on the crate. Assume friction is negligible. Which graph best shows the velocity of the crate over time?

Three pairs of charges, X, Y, and Z, are shown.

Which of the following correctly orders the pairs of charges by the magnitude of the forces between the charges in each pair?

The diagram shows a worker pushing a crate from the bottom of a ramp to the top of the ramp.

The worker does 1900 J of work on the crate to push it to the top of the ramp. The crate has a gravitational potential energy of 1200 J at the top of the ramp. What is the efficiency of the worker pushing the crate from the bottom to the top of the ramp?

A 0.23B 0.37C 0.58D 0.63

A circuit includes a battery and three resistors, as shown.

What is the total resistance of the circuit?

A 2 ΩB 19 ΩC 28 ΩD 240 Ω

A car is traveling with an initial velocity of 30 m/s. Over 6 s, the car slows to a final velocity of 18 m/s.

What is the magnitude of the car’s average acceleration during the 6 s?

A 2 m/s²B 3 m/s²C 5 m/s²D 8 m/s²

In an investigation, the temperature of a 1 kg sample of liquid ethanol was initially 0°C. As energy was added to the sample, the temperature of the ethanol was recorded in a graph, as shown. Assume no energy was transferred to the surroundings.

Part A: Which of the following best describes the sample of ethanol?

A The ethanol melted below 78°C.
B The ethanol froze at about 78°C.
C The ethanol remained a liquid above 78°C.
D The ethanol began changing into a gas at about 78°C

Part B: The investigation was repeated with a 0.5 kg sample of ethanol instead of a 1.0 kg sample. Which graph best represents the temperature of the 0.5 kg sample of ethanol as energy was added?

The diagram shows a 900 kg hot air balloon. Only two forces are acting on the balloon, a 9000 N gravitational force and a 9500 N lift force.

What is the acceleration of the balloon?

A 0.21 m/s² upwardB 0.21 m/s² downwardC 0.56 m/s² upwardD 0.56 m/s² downward

Which of the following has the lowest average molecular kinetic energy?

A steam in a pipeB ice cubes in a cupC water boiling in a panD water flowing in an aquarium

A 30 kg object moving at 10 m/s is used to test the strength of a material. The object collides with the material and comes to a stop. The average force on the object is 15,000 N. What is the amount of time of the collision?

A 0.0006 sB 0.001 sC 0.02 sD 0.33 s

The following section focuses on sound and light waves produced by an electronic game.

Read the information below and use it to answer the selected-response questions and constructed-response question that follow.

One type of handheld electronic game is known as a random sequence game (RSG). The object of the game is to try to repeat a unique sequence of light and sound signals produced by the RSG. The player does this by pressing the game’s four color buttons in the correct order. The color buttons produce equally bright lights and equally loud sounds when pressed.

Each color button, however, produces a different color of light and a different pitch of sound. The game is shown in the illustration.

The table shows the frequency of the sound and the wavelength of the light that each button produces.

Part A: A player presses the blue button on the RSG, which produces a blue light wave and a sound wave. The player’s friend is standing 3 m away. Which wave reaches the player’s friend first?

A. the blue light waveB. the sound wave

Part B:Which of the following best explains why this wave reaches the player’s friend first?

A. The wave travels the same distance in more time than the other wave.
B. The wave travels the same distance in less time than the other wave.

If an astronaut tried to use the RSG while standing on the Moon, the astronaut would not be able to hear the game’s sound but would be able to see the game’s light. Which of the following best describes the sound and light waves?

A. Sound waves are transverse waves, and light waves are longitudinal waves.
B. Sound waves are mechanical waves, and light waves are longitudinal waves.
C. Sound waves are transverse waves, and light waves are electromagnetic waves.
D. Sound waves are mechanical waves, and light waves are electromagnetic waves.

Which of the following correctly compares a sound wave emitted by the green color button with a sound wave emitted by the blue color button?

A The sound wave emitted by the green color button would have a larger amplitude.
B The sound wave emitted by the green color button would have a smaller amplitude.
C The sound wave emitted by the green color button would have a longer wavelength.
D The sound wave emitted by the green color button would have a shorter wavelength.

This question has three parts. Write your response on the next page. Be sure to label each part of your response.

A student pressed the red color button on the RSG, which produced a sound wave that traveled at 343 m/s through air.

Part A: The diagram shows the sound wave produced by the red button, with six arrows labeled P, Q, R, S, T, and U.

Identify the arrow (P, Q, R, S, T, or U) in the diagram that represents a wavelength of the sound.

Part B: Calculate the wavelength of the sound produced by the red button. Show your calculations and include units in your answer.

Part C: Calculate the period of the sound produced by the red button. Show your calculations and include units in your answer.

The graph shows the change in position of an object over time.

At which of the following times did the object have a velocity of 0 m/s?

A 1 sB 4 sC 7 sD 9 s

Which of the following free-body force diagrams shows an object with zero net force?

A 25 Ω resistor and a 100 V battery are connected in a series circuit. What is the current through the resistor?

A 0.3 AB 2.0 AC 4.0 AD 75 A

A student placed a compass directly on top of a wire. The student then connected each end of the wire to a battery. The diagrams show the compass and wire before and after the battery was connected.

Which of the following best describes why the compass needle moved?

A The metal of the wire generated a magnetic field strong enough to move the compass needle.
B The current in the wire generated a magnetic field strong enough to move the compass needle.
C The metal of the wire generated a gravitational field strong enough to move the compass needle.
D The current in the wire generated a gravitational field strong enough to move the compass needle.

This question has four parts. Write your response on the next page. Be sure to label each part of your response.

A material hoist is a device used to lift or lower heavy loads. The illustration shows a material hoist lifting two people whose combined mass is 160 kg.

Part A: Calculate the work done by the hoist to lift the two people 15 m. Show your calculations and include units in your answer.

Part B: Describe how the work done by the hoist to lift the two people 15 m compares to the change in gravitational potential energy of the two people. Support your answer by referring to variables in both the work and potential energy formulas.

Part C: The hoist is used to lift a 70 kg wooden beam to a height of 20 m. The beam then falls off the hoist. Describe what happens to the beam’s gravitational potential energy and the beam’s kinetic energy as it falls to the ground.

Part D: Calculate the velocity of the 70 kg beam just before it hits the ground. Show your calculations and include units in your answer.