Physical Science Take 10 Week # 4

Day #1 Question 1 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? A. Car X’s momentum increases, and car Y’s momentum decreases. B. Car X’s momentum decreases, and car Y’s momentum increases. C. Car X’s momentum is unchanged, and car Y’s momentum increases. D. Car X’s momentum is unchanged, and car Y’s momentum decreases.

Day #1 Question 2 Two students are standing next to each other. One of the students throws a tennis ball forward toward a line 2.0 m away. At the same time, the second student throws a bowling ball in the same direction. Both balls take the same time to travel the 2.0 m. Only the second student feels a noticeable backward push when she throws her ball. Which of the following statements explains why only the second student feels a noticeable backward push? A. The bowling ball exerts a much larger reaction force. B. The bowling ball undergoes a much larger acceleration. C. The bowling ball requires more force to overcome gravity. D. The bowling ball converts more inertia into kinetic energy.

Day #1 Answers Car X collides with car Y. How does the momentum of each car change after the collision? B. Car X’s momentum decreases, and car Y’s momentum increases. 2. Which of the following statements explains why only the second student feels a noticeable backward push? A. The bowling ball exerts a much larger reaction force.

Day #2 Question 1 The diagram shows the forces acting on a rock. The weight of the rock is 76 N. An upward force of 106 N is exerted on the rock. What is the net force acting on the rock? A. 106 N upward B. 76 N downward C. 30 N upward D. 182 N downward

Day #2 Question 2 A car has an oil drip. As the car moves, it drips oil at a regular rate, leaving a trail of spots on the road. Which of the following diagrams the car continuously slowing down?

Day #2 Answers 1. What is the net force acting on the rock? A. 30 N upward 2. Which of the following diagrams of the car’s trail of spots shows the car continuously slowing down?

Day #3 Questions 1. Which of the following is an example of velocity? A. A ball has an instantaneous speed of 15 m/s. B. An object has a mass of 10.5 kg. C. A 1.0 kg object moves at 18 m/s. D. A student walks 2.0 m/s north. 2. Which of the following statements best explains why it is usually easier to keep a sliding object moving than it is to start the object moving? A. Kinetic friction is typically equal to static friction. B. Kinetic friction is typically less than static friction. C. Kinetic friction is a force that resists attempts to start an object moving. D. Kinetic friction is a force that opposes the sliding of two objects over each other.

Day #3 Answers 1. Which of the following is an example of a velocity? D. A student walks 2.0 km/s north. 2. Which of the following statements best explains why it is usually easier to keep a sliding object moving than it is to start the object moving? B. Kinetic friction is typically less than static friction.

Day #4 Question 1 Mike, who has a mass of 75 kg, is running north at 2.6 m/s. He 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? A. Mike has a momentum of 130 kg • m/s north, and Tom has no momentum. B. Both Mike and Tom have a momentum of 130 kg • m/s north. C. Mike has a momentum of 195 kg • m/s north, and Tom has no momentum. D. Both Mike and Tom have a momentum of 195 kg • m/s north.

Day #4 Question 2 The illustration 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 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? A. P B. Q C. R D. S

Day #4 Answers 1. Which of the following statements describes how much momentum each person has before the collision? C. Mike has a momentum of 195 kg • m/s north, and Tom has no momentum. 2. Which arrow shows the direction of the centripetal force on the ball before the ball is released? D. S

Day #5 Question 1 A cart with a mass of 5 kg rests on a floor next to a wall. 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? A. The wall does not push on the cart. B. The floor pushes 100 N up on the cart. C. The cart pushes 100 N down on the floor. D. The wall pushes 100 N to the right on the cart.

Day #5 Question 2 A performer pulls a tablecloth out from under a complete set of dinnerware. Which of the following best explains the performer’s success at leaving all the dinnerware on the table? A. the inertia of the dinnerware B. the large mass of the tablecloth C. the placement of the dinnerware D. the rough material of the tablecloth

Day #5 Answers 1. 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? D. The wall pushes 100 N to the right on the cart. 2. Which of the following best explains the performer’s success at leaving all the dinnerware on the table? A. the inertia of the dinnerware