Physics Concept Questions for Test on Motion

Two ice skaters, Paul and Tom, are each holding on to opposite ends of the same rope. Each pulls the other toward him. The magnitude of Paul's acceleration is 1.25 times greater than the magnitude of Tom's acceleration. What is the ratio of Paul's mass to Tom's mass? 1.25 0.80 0.50 0.25 0.67

0.80

The drawing shows a block at rest on an incline. The mass of the block is 8.0 kg. What is the static frictional force that acts on the block? 73 N 32 N 78 N 29 N There is not enough information to calculate the frictional force.

29N

Two identical boxes are being pulled across a horizontal floor at a constant velocity by a horizontal pulling force of 176 N that is applied to one of the boxes, as the drawing shows. There is kinetic friction between each box and the floor. Find the tension in the rope between the boxes. 176 N 88.0 N 132 N 44.0 N There is not enough information to calculate the tension.

88.0 N

A cup of coffee is sitting on a table in a recreational vehicle (RV). The cup slides toward the rear of the RV. According to Newton's first law, which one or more of the following statements could describe the motion of the RV? (A) The RV is at rest, and the driver suddenly accelerates. (B) The RV is moving forward, and the driver suddenly accelerates. (C) The RV is moving backward, and the driver suddenly hits the brakes. A B C A and B A, B, and C

A, B, and C

A car has a mass of 1600 kg. It is stuck in the snow and is being pulled out by a cable that applies a force of 7560 N due north. The resistance of the snow and mud also applies a force to the car, which has a magnitude of 7340 N and points due south. What is the acceleration of the car? A.) 0.14 m/s2 north B.) 4.7 m/s2 north C.) 4.6 m/s2 south D.) 9.3 m/s2 south E.) There is not enough information to determine the car's acceleration.

A.) 0.14 m/s^2 north

Two forces act on a moving object that has a mass of 27 kg. One force has a magnitude of 12 N and points due south, while the other force has a magnitude of 17 N and points due west. What is the acceleration of the object? A.) 0.77 m/s2 directed 35° south of west B.) 1.1 m/s2 directed 35° south of west C.) 0.77 m/s2 directed 55° south of west D.) 0.63 m/s2 directed 55° south of west E.) 0.44 m/s2 directed 24° south of west

A.) 0.77m/s^2 directed 35 south of west

A cheetah has an acceleration that has x and y components of ax = 5.3 m/s2 and ay = 3.8 m/s2. The cheetah's mass is 61 kg. Find the net force acting on the cheetah. A.) 4.0 × 102 N, directed 36º above the x axis B.) 3.2 × 102 N, directed 36º above the x axis C.) 2.3 × 102 N, directed 54º above the x axis D.) 5.6 × 102 N, directed 36º above the x axis E.) 4.0 × 102 N, directed 54º above the x axis

A.) 4.0 × 102 N, directed 36º above the x axis

Which one of the following objects is in equilibrium? A.) A space probe with its engines shut down, moving through a vast empty region of outer space. B.) A projectile as it passes through the topmost point of its trajectory. C.) A brick falling from a bridge. D.) A race horse taking off at the beginning of a race. E.) A taxi coming to a halt to discharge a passenger.

A.) A space probe with its engines shut down, moving through a vast empty region of outer space

The apparent weight of a passenger in an elevator is greater than his true weight. Which one of the following is true? A.) The apparent weight of a passenger in an elevator is greater than his true weight. Which one of the following is true? B.) The elevator is either moving upward with a decreasing speed or moving downward with an increasing speed. C.) The elevator is either moving upward with an increasing speed or moving upward with a decreasing speed. D.) The elevator is either moving upward with an increasing speed or moving downward with an increasing speed. E.) The elevator is either moving upward with a decreasing speed or moving downward with a decreasing speed.

A.) The apparent weight of a passenger in an elevator is greater than his true weight. Which one of the following is true?

Which one of the following descriptions violates Newton's first law of motion? A.) A small suitcase is at the front of the overhead luggage compartment on an airplane. When the airplane begins its takeoff, the suitcase slides to the rear of the compartment. B.) A rabbit's foot is hanging on a chain from the rearview mirror of a car. As the car accelerates, the rabbit's foot swings toward the windshield. C.) A glass of water is sitting on a table in the dining car of a train. The train brakes as it nears the station, and the glass slides forward. D.) A child is sitting in the back seat of a car and is not wearing a seat belt. The car is traveling forward, and the driver suddenly applies the brakes. The child flies forward against the rear side of the front seat.

B.) A rabbit's foot is hanging on a chain from the rearview mirror of a car. As the car accelerates, the rabbit's foot swings toward the windshield.

A certain object is not in equilibrium. Three of the following statements could possibly be true, and one must be true. Which one of the following must be true? A.) Only three forces act on the object. B.) Only a single force acts on the object. C.) A net force acts on the object. D.) Only two perpendicular forces act on the object.

C.) A net force acts on the object

A certain object is in equilibrium. Which one of the following statements is not true? A.) The object has a constant velocity. B.) No net force acts on the object. C.) The object must be at rest. D.) The object has no acceleration.

C.) The object must be at rest

An object is moving at a constant velocity. All but one of the following statements could be true. Which one cannot be true? A.) No forces act on the object. B.) Two forces act simultaneously on the object. C.) Three forces act simultaneously on the object. D.) A single force acts on the object.

D.) A single force acts on the object

Which one of the following is true, according to Newton's laws of motion? Ignore friction. A.) A sports utility vehicle (SUV) hits a stationary motorcycle. Since it is stationary, the motorcycle sustains a greater force than the SUV does. B.) A semitrailer truck crashes all the way through a wall. Since the wall collapses, the wall sustains a greater force than the truck does. C.) Sam (18 years old) and his sister (9 years old) go ice skating. They push off against each other and fly apart. Sam flies off with the greater acceleration. D.) Two astronauts on a space walk are throwing a ball back and forth between each other. In this game of catch the distance between them remains constant. E.) None of the these is true, according to the third law

E.) None Not A or B because third law, which states that whenever one body exerts a force on a second body, the second body exerts an oppositely directed force of equal magnitude on the first body. C is wrong according to the third law, Sam and his sister experience forces of equal magnitudes during the push-off. Since Sam has the greater mass, he flies off with the smaller acceleration, according to the second law. D is wrong because in catching and throwing the ball each astronaut applies a force to it, and, according to the third law, the ball applies an oppositely directed force of equal magnitude to each astronaut. These reaction forces accelerate the astronauts away from each other, so that the distance between them increases.

The drawings show three identical blocks sliding along horizontal surfaces. Each block has a different mass, as indicated. The coefficient of kinetic friction in each case is the same. Which block has the greatest deceleration? A B C The deceleration is the same in each case.

The deceleration is the same