Forces and Newton's Laws of Motion

Forces and Newton's Laws of Motion

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1) In a collision between a huge SUV and a small hybrid car, the SUV exerts a larger force on the hybrid than the hybrid exerts on the SUV.

Forces and Newton's Laws of Motion

A) True

B) False

C) It depends on whether the collision is a head-on collision or a rear-end collision.

Forces and Newton's Laws of Motion

2) A box is placed on a table which rests on the floor. The box pushes on the table; the reaction force to the box's push on the table is the table's push on the floor.

Forces and Newton's Laws of Motion

A) True

B) False

Forces and Newton's Laws of Motion

3) In order to get an object moving, you must push harder on it than it pushes back on you.

Forces and Newton's Laws of Motion

A) True

B) False

Forces and Newton's Laws of Motion

4) If the rockets of a spaceship in outer space (far from all gravity) suddenly lose power and go off, the spaceship will gradually slow to a stop.

Forces and Newton's Laws of Motion

A) True

B) False

Forces and Newton's Laws of Motion

5) You are in a train traveling on a horizontal track and notice that a piece of luggage starts to slide directly toward the front of the train. From this observation, you can conclude that this train is

Forces and Newton's Laws of Motion

A) speeding up.

B) slowing down.

C) changing direction.

D) speeding up and changing direction.

E) slowing down and changing direction.

Forces and Newton's Laws of Motion

6) While flying horizontally in an airplane, you notice that a string dangling from the overhead luggage compartment hangs at rest at 15° away from the vertical toward the front of the plane. Using this observation, you can conclude that the airplane is

Forces and Newton's Laws of Motion

A) moving forward.

B) moving backward.

C) accelerating forward.

D) accelerating backward.

E) not accelerating because the string is at rest.

Forces and Newton's Laws of Motion

7) An elevator suspended by a vertical cable is moving downward but slowing down. The tension in the cable must be

Forces and Newton's Laws of Motion

A) greater than the weight of the elevator.

B) less than than the weight of the elevator.

C) equal to the weight of the elevator.

Forces and Newton's Laws of Motion

8) A crate is sliding down an inclined ramp at a constant speed of 0.55 m/s. The vector sum of all the forces acting on this crate must point

Forces and Newton's Laws of Motion

A) down the ramp.

B) up the ramp.

C) perpendicular to the ramp.

D) vertically downward.

E) None of the above choices is correct.

Forces and Newton's Laws of Motion

9) A golf club hits a golf ball with a force of 2400 N, sending the ball into the air. The force exerted on the club by the ball must be less than 2400 N or else the ball would not have moved forward.

Forces and Newton's Laws of Motion

A) True

B) False

C) The answer depends on whether the golfer followed through with the swing.

Forces and Newton's Laws of Motion

10) A 75-N box rests on a perfectly smooth horizontal surface. The minimum force need to start the box moving is

Forces and Newton's Laws of Motion

A) 75 N.

B) 7.5 N.

C) 750 N.

D) any horizontal force greater than zero.

Forces and Newton's Laws of Motion

11) The acceleration due to gravity is lower on the Moon than on Earth. Which one of the following statements is true about the mass and weight of an astronaut on the Moon's surface, compared to Earth?

Forces and Newton's Laws of Motion

A) Mass is less, weight is the same.

B) Mass is the same, weight is less.

C) Both mass and weight are less.

D) Both mass and weight are the same.

Forces and Newton's Laws of Motion

12) When a 45-kg person steps on a scale in an elevator, the scale reads a steady 480 N. Which of the following statements must be true? (There could be more than one correct choice.)

A) The elevator is accelerating upward at a constant rate.

B) The elevator is accelerating downward at a constant rate.

C) The elevator is moving upward at a constant rate.

D) From the given information, we cannot tell if the elevator is moving up or down.

13) On its own, a tow truck has a maximum acceleration of 3.0 m/s2. What will be its maximum acceleration when the truck is using a light horizontal chain to tow a bus of twice its own mass?

Forces and Newton's Laws of Motion

A) 2.5 m/s2

B) 2.0 m/s2

C) 1.5 m/s2

D) 1.0 m/s2

Forces and Newton's Laws of Motion

14) A car of mass 1100 kg that is traveling at 27 m/s starts to slow down and comes to a complete stop in 578 m. What is the magnitude of the average braking force acting on the car?

Forces and Newton's Laws of Motion

A) 690 N

B) 550 N

C) 410 N

D) 340 N

Forces and Newton's Laws of Motion

15) A certain aircraft has a mass of 300,000 kg. At a certain instant during its landing, its speed is 27.0 m/s. If the braking force is a constant 445,000 N, what is the speed of the airplane 10.0 s later?

Forces and Newton's Laws of Motion

A) 10.0 m/s

B) 12.2 m/s

C) 14.0 m/s

D) 18.0 m/s

E) 20.0 m/s

Forces and Newton's Laws of Motion

16) The figure shows an acceleration-versus-force graph for three objects pulled by wires. If the mass of object 2 is 36 kg, what are the masses of objects 1 and 3?

Forces and Newton's Laws of Motion

A) 12 kg and 90 kg

B) 72 kg and 18 kg

C) 90 kg and 12 kg

D) 12 kg and 72 kg

Forces and Newton's Laws of Motion

Applying Newton's Laws

17) In the figure, a 10-lb weight is suspended from two spring scales, each of which has negligible weight. Which one of the following statements about the readings in the scales is true?

A) Each scale will read 5 lb.

B) The top scale will read zero, the lower scale will read 10 lb.

C) The lower scale will read zero, the top scale will read 10 lb.

D) Each scale will show a reading between one and 10 lb, such that the sum of the two is 10 lb. However, exact readings cannot be determined without more information.

E) None of these is true.

18) Two blocks, A and B, are being pulled to the right along a horizontal surface by a horizontal 100-N pull, as shown in the figure. Both of them are moving together at a constant velocity of 2.0 m/s to the right, and both weigh the same.

Which of the figures below shows a correct free-body diagram of the horizontal forces acting on the upper block, A?

Forces and Newton's Laws of Motion

19) Two blocks, A and B, are being pulled to the right along a horizontal surface by a horizontal 100-N pull, as shown in the figure. Both of them are moving together at a constant velocity of 2.0 m/s to the right, and both weigh the same.

Which of the figures below shows a correct free-body diagram of the horizontal forces acting on the lower block, B?

Forces and Newton's Laws of Motion

E) None of these diagrams is correct.

Forces and Newton's Laws of Motion

20) A push of magnitude P acts on a box of weight W as shown in the figure. The push is directed at an angle θ below the horizontal, and the box remains a rest. The box rests on a horizontal surface that has some friction with the box. The friction force on the box due to the floor is equal to

Forces and Newton's Laws of Motion

A) P sin θ

B) P cos θ

C) 0

D) P cos θ + W

E) P + W

Forces and Newton's Laws of Motion

21) In the figure, what does the spring scale read? The pulleys are ideal and the strings and scale are also massless.

Forces and Newton's Laws of Motion

A) exactly 2.0 N.

B) exactly 1.0 N

C) 0.50 N

D) 0.00 N

E) more than 19.6 N

Forces and Newton's Laws of Motion

22) Two objects of unequal masses, M and m (Mm), are connected by a very light cord passing over an ideal pulley of negligible mass. When released, the system accelerates, and friction is negligible.

Which one of the following free-body diagrams most realistically represents the forces acting on the two objects in the moving system?

Forces and Newton's Laws of Motion

23) A 200-N sled of slides down a frictionless hillside that rises at 37° above the horizontal. What is the magnitude of the force that the surface of the hill exerts on the sled?

Forces and Newton's Laws of Motion

A) 200 N

B) 120 N

C) 160 N

D) 150 N

E) 0 N

Forces and Newton's Laws of Motion

24) A 10-kg sign is held by two ropes as shown in the figure. What is the tension on rope A?

Forces and Newton's Laws of Motion

A) 44 N

B) 69 N

C) 72 N

D) 88 N

E) 98 N

Forces and Newton's Laws of Motion

25) A 3.0-kg and a 5.0-kg box rest side-by-side on a perfectly smooth, level floor. A horizontal force of 32 N is applied to the 3.0-kg box pushing it against the 5.0-kg box, and, as a result, both boxes slide along the floor. How hard do the two boxes push against each other?

Forces and Newton's Laws of Motion

A) 12 N

B) 20 N

C) 24 N

D) 32 N

E) 0 N

Forces and Newton's Laws of Motion

26) A 3.0-kg mass and a 5.0-kg mass hang vertically at the opposite ends of a very light rope that goes over an ideal pulley. If the masses are gently released, what is the resulting acceleration of the masses?

Forces and Newton's Laws of Motion

A) 0.00 m/s2

B) 3.7 m/s2

C) 2.5 m/s2

D) 4.9 m/s2

E) 6.1 m/s2

Forces and Newton's Laws of Motion

27) The figure shows a 100-kg block being released from rest from a height of 1.0 m. It then takes 0.53 s for it to reach the floor. What is the mass m of the block on the left? There is no friction or mass in the pulley, and the connecting rope is very light.

Forces and Newton's Laws of Motion

A) 16 kg

B) 14 kg

C) 13 kg

D) 11 kg

Forces and Newton's Laws of Motion

28) A policeman investigating an accident measures the skid marks left by a car on the horizontal road. He determines that the distance between the point that the driver slammed on the brakes (thereby locking the wheels) and the point where the car came to a stop was 28.0 m. From a reference manual he determines that the coefficient of kinetic friction between the tires and the road under the prevailing conditions was 0.300. How fast was the car going when the driver applied the brakes?

Forces and Newton's Laws of Motion

A) 10.7 m/s

B) 12.8 m/s

C) 21.4 m/s

D) 32.9 m/s

E) 45.7 m/s

Forces and Newton's Laws of Motion

29) Jason takes off across level water on his jet-powered skis. The combined mass of Jason and his skis is 75 kg (the mass of the fuel is negligible). The skis produce a forward thrust of 200 N and have a coefficient of kinetic friction with water of 0.10. Unfortunately, the skis run out of fuel after only 90 s. What is Jason's top speed?

Forces and Newton's Laws of Motion

A) 150 m/s

B) 240 m/s

C) 24 m/s

D) 90 m/s

Forces and Newton's Laws of Motion

30) A 50.0-kg block is being pulled up a 16.0° slope by a force of 250 N that is parallel to the slope. The coefficient of kinetic friction between the block and the slope is 0.200. What is the acceleration of the block?

Forces and Newton's Laws of Motion

A) 0.528 m/

B) 0.158 m/

C) 0.412 m/

D) 0.983 m/

E) 0.260 m/

Forces and Newton's Laws of Motion