 MCAS Physics Exams MCAS 2008 Session 1 Radio waves, visible light, and x-rays are examples of electromagnetic waves that always differ from each other in Two oppositely charged objects are separated by a small distance. The objects are then moved three times farther apart from each other. Which of the following statements best describes what happens to the electrical force between the objects? A sound wave can be transmitted through all of the following except Three different boxes are lifted to different heights.

• >Box X weighs 115 N and is lifted to 15 m.
• Box Y weighs 210 N and is lifted to 10 m.
• >Box Z weighs 305 N and is lifted to 5 m. Which of the following statements applies to a longitudinal wave? An ammeter measures the current in the circuit shown below. When the piece of wire labeled X is replaced by a second identical R, which of the following happens to the current? A magnetic compass is placed near an insulated copper wire. When the wire is connected to a battery, the compass needle changes position. Which of the following is the best explanation for the movement of the needle? Mike, who has a mass of 75 kg, is running north at 2.6 m/s. He accidentally collides with Tom, who has a mass of 125 kg and is not moving. Which of the following statements describes how much momentum each person has before the collision? X-ray waves and infrared waves are both electromagnetic waves. Which of the following describes another property x-ray waves and infrared waves share? A recycling plant manager needs to melt 1500 kg of scrap copper to sell to a wire manufacturer. The copper is at 15°C and its melting point is 1083°C. The copper has a specific heat of 385 J/kgK.

How much heat is required to raise the temperature of the copper to its melting point? The illustration below shows an athlete participating in an Olympic hammer throw event. The athlete twirls the hammer (a heavy steel ball attached to a wire) around several times before releasing it. The diagram below shows the path of the ball as it is spun in a circle before its release. >Which arrow shows the direction of the centripetal force on the ball before the ball is released? Suppose a scientist detects an electromagnetic wave with a frequency higher than those of gamma rays. The scientist labels this wave a Z-ray. Which of the following would always be true of a Z-ray? The power of a toaster can be determined if which of the following values are known? In the diagram below, the circuit has one battery and two identical light bulbs. If one light bulb is removed, which of the following could replace it so that the remaining light bulb is dimmer? A cart with a mass of 5 kg rests on a floor next to a wall, as shown in the diagram below. A person pushes on the cart to the left toward the wall with a force of 100 N. Which of the following statements is true in this situation? How much power is required to carry a 35 N package a vertical distance of 18 m if the work on the package is accomplished in 30 s? The graph below illustrates the position and time for a dog that runs to catch a stick and then returns with it. The dog caught the stick after 2 s. What was the dog’s average speed as he returned with the stick? A heavy box is at rest on an inclined plane. The box begins to slide down the inclined plane when a small force is applied to the box. The force is removed as soon as the box begins to slide. The speed of the box increases as the box slides down the inclined plane. Which of the following is the most likely cause of this increasing speed? A 1500 kg car has an applied forward force of 5000 N and experiences an air resistance of 1250 N. What is the car’s acceleration? Measurements inside a sealed container show that the pressure exerted by a gas increases as the thermal energy of the gas increases. Which of the following best explains this pressure increase? On the surface of the Moon, a ball is thrown straight up with an initial velocity. The ball has a constant acceleration due to the Moon’s gravity. On a graph of the ball’s velocity versus time, which of the following would represent the ball at its highest point above the Moon’s surface?

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 three questions. In the diagram below, the falling water turns the waterwheel. The turning waterwheel generates electricity. The water moves slowly at point A and then falls rapidly past point B.
 a.  Describe the changes in kinetic and gravitational potential energy of the water as it travels from point A to point B.

 b.  Explain why not all of the energy of the moving water available at point A is captured by the waterwheel to generate electricity.

 c.  Describe two ways the system can be changed so that more energy from the falling water is converted into electrical energy.

Refer to the following information for the next four questions. In an experiment, liquid 1 is at room temperature (21ºC) and liquid 2 has been heated until it is warmer than room temperature. A student takes equal amounts of liquid 1 and liquid 2 and mixes them together in a beaker.

 a. Compare the initial temperatures of liquid 1 and liquid 2 with the temperature of the mixture in the beaker at each of the following times:    - 5 minutes after mixing

 - 2 hours after mixing

 b.  Describe the transfer of heat energy between the two liquids in the beaker.

 c.  Identify one other possible heat energy transfer in this experiment.