 MCAS Physics Exams MCAS 2007 Session 1 A car is parked on the side of a hill. Which of the following most likely prevents the car from moving down the hill? Thermal energy is added to four identical 1.0 kg samples of water at room temperature. Which of the following increases in each sample? A current of 2 A passes through two resistors placed in series. The first resistor has a resistance of 10 ohms and the second resistor has a resistance of 20 ohms. What is the total potential difference across the two resistors? The diagram below shows a wave generator that emits a wave with a frequency of 500 Hz and a wavelength of 0.1 m. How long does it take for the wave to travel a distance of 2000 m? A hockey player swings her hockey stick and strikes a puck. According to Newton’s third law of motion, which of the following is a reaction to the stick pushing on the puck? To make ice, water must first be cooled. The specific heat of water is 4,186 J/kg • °C. Approximately how much heat must be removed from 0.50 kg of water to change its temperature from 24°C to 5°C? The diagrams below show a cart moving with a velocity, V, on a frictionless surface as a wooden block is being dropped. The block then falls straight down onto the moving cart. Which of the following statements describes what will happen after the block lands on the moving cart? A cart at the top of a hill is released and rolls down the hill. Which of the following describes the energy of the cart just as it reaches the bottom of the hill? When one end of a short metal bar is heated, the opposite end will eventually become hot. Which of the following processes transfers the heat through the bar? Which of the following will definitely cause a change in the velocity of a parked car? A rise in the temperature inside a kitchen means there is an increase in the Which of the following provides the best example of simple harmonic motion? Jessica places 1000 g of water at 20.0°C in an insulated cup. The specific heat capacity of water is 4.20 J/g • °C. What is the final temperature of the water if 5000 J of energy is added to the water in the insulated cup? Which of the following is a vector quantity? Two identical beakers each contain 250 mL of water. The temperature of the water is 85°C in one beaker and 15°C in the other beaker. A drop of red food coloring is placed in each beaker at the same time. During the first minute, which of the following is most likely to happen? The graph below relates the current to voltage data for a resistor. Which of the following is the value of the resistor? The illustration below shows wave traces of recorded sound waves on two computer screens. Traces A and B represent two different sounds with the same time scale horizontally. From a comparison of the wave traces, which of the following correctly describes the relationship of sound B to sound A? What is the mass of an object weighing 63 N on Earth? Which of the following is least likely to result in the generation of static charge? The two resistors shown below are connected to identical power sources. Resistor 1 has a resistance of 30 ohms, and resistor 2 has a resistance of 45  ohms. The current in resistor 1 is 2 A. What is the current in resistor 2? The distance between Earth and the Moon was determined by measuring the time it took for light waves from Earth to travel to the Moon and back. Why was it not possible to use sound waves for this experiment? Which of the following requires the greatest amount of heat? If heat is added to a liquid, which of the following occurs?

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. A student rubs a balloon on her hair and the balloon acquires a negative charge.
 a.  Explain why the balloon acquires a negative charge.

 b.  After the balloon is rubbed on the student’s head, the student’s hair stands out from her head. Explain why this happens.

 The student then brings the negatively charged balloon near another balloon that was charged in the same way.    c.  Describe and explain what happens when the negatively charged balloon is brought near another negatively charged balloon.

Refer to the following information for the next four questions. On a smooth, level surface, a red marble of mass 0.02 kg moving at 2.0 m/s collides with a stationary yellow marble of equal mass. After the collision, the red marble stops completely, and the yellow marble moves in the direction the red marble was moving.
 a. Calculate the momentum of both marbles before the collision.

 b. Calculate the momentum of both marbles after the collision.

 c. If the velocity of the red marble doubles, how will the velocity of the yellow marble change after the collision?

 d. If the red marble had more mass than the yellow marble, how would the momentum of the yellow marble change after the collision?

Refer to the following information for the next four questions. The drawing below shows two students holding the ends of a spring that has a ribbon attached to it. a. Draw and explain how a transverse wave will move along the spring.

 b. Draw and explain how the ribbon will move when a transverse wave is sent along the spring.

 c. Draw and explain how a longitudinal wave will move along the spring.

 d. Draw and explain how the ribbon will move when a longitudinal wave is sent along the spring.