MCAS Physics Exams MCAS 2010 Session 1
A balloon is inflated with room-temperature air and then put in a sunny place. The balloon expands slightly due to a rise in temperature. Which of the following best describes the molecules of air inside the balloon when the balloon is left in the sunlight as compared to when it was first inflated?

Four students push on a block of wood with the forces shown in the diagram below. Assume friction is negligible.

The block slides horizontally. What is the net force acting on the block of wood?
A cup containing 25 mL of hot water and a similar cup containing 25 mL of cold water are placed on a table in a room at 21°C. Which of the following graphs shows the most likely change in temperature for each cup from 0 min to 40 min?

Which of the following properties is the same for all electromagnetic waves in a vacuum?
An elevator in an office building completed the following trips:

• 1st floor to 8th floor
• 8th floor to 4th floor
• 4th floor to 13th floor

The distance between each floor of the office building is 3.0 m.

Which table shows the total distance traveled and displacement of the elevator?

Which of the following conditions results in the buildup of static charge on an object?

What is the voltage across the terminals of a 23 Ω resistor that has 0.065 A of current flowing through it?
The momentum of an object in space is
Which of the following is an example of heat transfer by conduction?

In a competition, weightlifter 1 lifts a 100 kg weight from the floor. Weightlifter 2 also lifts a 100 kg weight to the same height above the floor, but takes a longer time to do so.

Which of the following statements describes the work done and the power used by the weightlifters?

The graphs below give information for waves W and X. Both waves were produced in the same medium and are moving at the same speed.

Which of the following statements describes another property of these waves?

Which of the following properties determines a color in the visible light region of the electromagnetic spectrum?
The source of a sound is moving away from an observer who is standing still. How do the sound waves received by the observer compare with those emitted by the source?

The diagram below shows a simple electric circuit.

Which of the following statements describes the function of the battery?

When a student listens to music, sound waves propagate from the speaker to her ear. Which of the following is a physical description of this process?

Which of the following statements best describes the force of Earth’s gravity on a rocket moving upward?

A student swings a bat horizontally, making contact with a ball thrown to her. The ball leaves the bat, and the bat continues moving through the rest of the swing.

Which of the following statements describes the change in energy necessary to do work on the ball?

The diagram below shows copper wire wrapped around a cardboard tube, which is then attached to a galvanometer. A galvanometer detects and measures small amounts of electric current.

Which of the following would cause the galvanometer needle to move?

A star suddenly explodes. Which of the following types of waves reach Earth’s surface?
A ball is thrown straight upward. The ball’s initial speed is 30 m/s and its mass is 0.05 kg, resulting in an initial kinetic energy of 22.5 J. If the initial potential energy of the ball is 10 J and there is no frictional force, what would be the ball’s total energy while it is moving?
At an amusement park, bumper car X moves at a speed of 2.5 m/s toward car Y, which is at rest, as shown in the diagram below.

Car X collides with car Y. How does the momentum of each car change after the collision?

Which of the following actions would increase the current through a circuit component?

The specific heat of wood is about 1,700 J/ kg • °C. How much energy is required to heat a 12 kg piece of wood from 20°C to 30°C?

Open-Response Questions
• BE SURE TO ANSWER AND LABEL ALL PARTS OF THE QUESTION.
• If you do the work in your head, explain in writing how you did the work.

Refer to the following information for the next two questions.

A car’s brakes absorb a large amount of energy and heat up as the car slows down and stops. Several materials with different thermal properties have been used for car brakes. In the table below, the specific heat capacities of three of these materials are shown.

In an experiment, 500-g each of aluminum, carbon-ceramic, and steel are heated and their temperature changes are recorded. The amount of heat absorbed and the temperature change for the 500-g sample of steel are shown in the graph below.

 a. In your Student Answer Booklet, copy the graph.       • Draw a line on your graph to show the relationship expected for the 500-g sample of aluminum.     • Draw a line on your graph to show the relationship expected for the 500-g sample of carbon-ceramic.     • Identify each line on your graph, and explain why you drew each line where you did.

 b. If brake materials get too hot they soften or melt, resulting in loss of braking power. Of the three materials in the table, which is best suited to resist large changes in temperature? Explain your answer.

Refer to the following information for the next three questions.

A student is conducting experiments with a block of wood. In experiment 1, the student pulls the block of wood with a constant force of 10 N along a horizontal surface. In experiment 2, the student pulls the same block of wood with a constant force of 10 N. The type of surface is different from that used in experiment 1. The results of experiments 1 and 2 are shown below.

 a.  Using information from the graphs, compare the surface in experiment 2 with the surface in experiment 1.

 b.  Determine both the magnitude of the force of friction and the net force on the block that are required to achieve the results shown in the graph for experiment 2. Include units in your answer.

 c.  Without changing the type of surface used when pulling the block of wood, list one other change to experiment 1 that would produce the results of experiment 2. Explain your reasoning with reference to the frictional force.