Forces and motion (Newton's laws)

9.The diagram shows a block on a frictionless surface being pulled by a force. If the mass of the block is doubled, what happens to its acceleration if the force remains the same?

10.Which law explains why a rocket moves forward by expelling gas backward?

11.An astronaut in space throws a wrench away from her. What happens to the astronaut?

12.A car of mass 1000 kg is moving at 20 m/s. The driver applies brakes and the car stops in 5 seconds. What is the average braking force?

13.A student pushes a book across a table with a constant force. The book moves at a constant speed. Which of the following is true about the forces acting on the book?

14.A 10 kg box is pulled with a force of 50 N to the right. The friction force is 20 N to the left. What is the acceleration of the box?

15.The graph shows the velocity of an object over time. During which interval is the net force on the object zero? (Assume motion is in a straight line.)

16.A 0.2 kg tennis ball is thrown horizontally at a wall. It hits the wall at 10 m/s and rebounds at 8 m/s in the opposite direction. The ball is in contact with the wall for 0.05 s. What is the average force exerted by the wall on the ball?

17.Two students push on opposite sides of a box. Student A pushes with 30 N to the right, and student B pushes with 20 N to the left. What is the net force on the box?

18.A rocket is launched into space. Which of Newton's laws best explains why the rocket moves forward?

19.A car of mass 1200 kg is moving at 15 m/s. The driver applies a braking force of 4000 N. How long will it take for the car to stop?

20.A table shows the results of an experiment where different forces are applied to a 2 kg object and the resulting acceleration is measured. Which of the following sets of data is consistent with Newton's second law?

21.A student places a book on a table. The book does not move. According to Newton's first law, this is because:

22.A 3 kg object accelerates at 2 m/s². What is the net force acting on it?

23.An astronaut in space (no friction) throws a wrench. The astronaut's mass is 80 kg, and the wrench's mass is 2 kg. The wrench moves away at 4 m/s. What is the astronaut's velocity after throwing the wrench?

24.A 500 g ball is kicked with a force of 40 N. What is the acceleration of the ball?

25.A student conducts an experiment to investigate Newton's second law. They apply different forces to a cart of constant mass and measure the resulting acceleration. Which graph best represents the relationship between net force and acceleration?

26.In a lab, a student uses a force sensor to pull a block across a surface at constant speed. The force sensor reads 2.5 N. What is the magnitude of the friction force acting on the block?

27.A student sets up an air track to minimize friction. A glider of mass 0.2 kg is pulled by a string over a pulley with a hanging mass of 0.05 kg. Assuming the pulley is frictionless and the string is massless, what is the acceleration of the glider? (Use g = 10 m/s²)

28.A student places a wooden block on a ramp and gradually increases the ramp angle. At a certain angle, the block just starts to slide. Which force is being overcome at that instant?

29.In an experiment to verify Newton's second law, a student uses a motion sensor to record the velocity of a cart as it is pulled by a constant force. The graph of velocity vs. time shows a straight line with slope 1.2 m/s². The cart's mass is 0.5 kg. What is the net force on the cart?

30.Two students push on opposite sides of a heavy box. Student A pushes with 50 N to the right, student B pushes with 30 N to the left. The box does not move. What is the magnitude of the friction force acting on the box?

31.A student measures the weight of an object using a spring scale. The scale reads 4.9 N. What is the mass of the object? (g = 9.8 m/s²)

32.A student investigates the relationship between force and acceleration using a dynamics cart. The cart is pulled by a string over a pulley with a hanging mass. The student increases the hanging mass and records acceleration. Which variable must be kept constant for a valid experiment?

33.A student uses a force sensor to measure the force exerted by a spring as it is stretched. The data show that the force is proportional to the extension. This is an example of which law?

34.In a collision experiment, two dynamics carts of equal mass are placed on a track. One cart is moving and hits a stationary cart. After the collision, the first cart stops and the second cart moves with the same speed as the first had initially. This best illustrates which law?

35.A student pushes a book across a table with a constant force. The book moves at a constant speed. Which statement about the forces is correct?

36.A student performs an experiment to measure the acceleration of a falling object using a ticker timer. The tape shows dots that are increasingly farther apart. What does this indicate about the motion?

37.Which of the following best describes Newton's first law of motion?

38.According to Newton's third law, if you push against a wall, the wall pushes back on you with an equal and opposite force. What is the reaction force?

39.During a collision, two objects exert forces on each other. According to Newton's third law, these forces have the same magnitude but opposite directions. What can be said about the accelerations of the two objects?

40.A 0.5 kg ball moving at 4 m/s hits a wall and rebounds at 3 m/s in the opposite direction. The collision lasts 0.1 s. What is the average force exerted on the ball by the wall?