Physics 011

PQ#4

Ayman A.Ghannam

 Name: S#: ID#: Sec:

 Chapter 4: Motion and Force: Dynamics Practice Questions

 1

A packing crate slides down an inclined ramp at constant velocity. Thus we can deduce that

a frictional force is acting on it.

a net force is acting on it.

it may be accelerating.

Gravity is not acting on it.

 2

You fall while skiing and one ski (of weight W) loosens and slides down an icy slope (assume no friction), which makes an angle q with the horizontal. The force that pushes it down along the hill is

zero; it moves with constant velocity.

W cos q

W sin q

it is not acted on by a gravitational force.

 3

A rope, tied between a motor and a crate, can pull the crate up a hill of ice (assume no friction) at constant velocity. The free-body diagram of the crate should contain

one force.

two forces.

three forces.

four forces.

 4

If two identical masses, attached by a massless cord passing over a massless, frictionless pulley of an Atwood's machine (at different heights), are released

the lower mass will go down.

the higher mass will go down.

the masses will not move.

the motion will depend on the actual value of each mass.

 5

The same horizontal force is applied to objects of different mass. Which of the following graphs illustrates the experimental results?

 6

A train consists of a caboose (mass = 1000 kg), a car (mass 2000 kg), and an engine car (mass 2000 kg). If the train has an acceleration of 5 m/s2, then the tension force in the coupling between the middle car and the engine car is

25,000 N

20,000 N

15,000 N

10,000 N

 7

A decoration, of mass M, is suspended by a string from the ceiling inside an elevator. The elevator is traveling upward with a constant speed. The tension in the string is

equal to Mg.

less than Mg.

greater than Mg.

impossible to tell without knowing the speed.

 8

Two identical masses are attached by a light string that passes over a small pulley, as shown. The table and the pulley are frictionless. The system is moving

with an acceleration less than g.

with an acceleration equal to g.

with an acceleration greater than g.

at constant speed.

 9

Two cardboard boxes full of books are in contact with each other on a frictionless table. Box H has twice the mass of box G. If you push on box G with a horizontal force F, then box H will experience a net force of

2/3 F

F

3/2 F

2 F

 10

A toolbox, of mass M, is resting on a flat board. One end of the board is lifted up until the toolbox just starts to slide. The angle theta that the board makes with the horizontal for this to occur depends on the

mass, M.

Gravity is not acting on it.

normal force.

coefficient of static friction, mu.

 11

Four students perform an experiment by pulling an object horizontally across a frictionless table. They repeat the experiment on several other objects of different masses, always applying just enough force to produce the same acceleration. They each graph the results, individually. Which student's graph is correct?

 12

An object is placed on an inclined plane. The angle of incline is gradually increased until the object begins to slide. The angle at which this occurs is q. What is the coefficient of static friction between the object and the plane?

sin q

cos q

tan q

Cannot determine without knowing the mass of the object.

 13

A mass on a string attached to a ceiling is pulled to the side and let go. When the string makes an angle q with the vertical, which of the following is not true?

The weight is down.

The tension equals mg*cos(q).

The tension equals mg*sin(q).

The tension and the weight are never in the same direction.

 14

A roller coaster car does a loop-the-loop. When it is upside down at the very top, which of the following is true?

The normal force and the weight are in opposite directions.

The normal force and the weight are perpendicular to each other.

The weight is zero.

The normal force and the weight are in the same direction.

 15

A roller coaster car does a loop-the-loop. When it is right-side up at the very bottom, which of the following is true?

The normal force and the weight are in opposite directions.

The normal force and the weight are perpendicular.

The weight is zero.

The normal force and the weight are in the same direction.

 16

A 2 kg box sits on a 3 kg box which sits on a 5 kg box. The 5 kg box rests on a table top. What is the normal force exerted on the 5 kg box by the table top?

19.6 N

29.4 N

49 N

98 N

 17

A 2 kg box sits on a 3 kg box which sits on a 5 kg box. The 5 kg box rests on a table top. What is the normal force exerted by the 5 kg box on the 3 kg box?

19.6 N

29.4 N

49 N

98 N

 18

A 5 kg (4.9 N) book rests on your desk. Which of the following answers is not correct?

The normal force on the book equals its weight because of Newton's First Law.

The normal force on the book equals its weight because of Newton's Second Law.

The normal force on the book equals the weight because of Newton's Third Law.

 19

A 5 kg (4.9 N) book rests on your desk. What is the reaction force to the 4.9 N weight (force) of the book?

The 4.9 N normal force from the table on the book.

The 4.9 N reaction force from the book on the table.

The weight of the earth.

A 4.9 N force on the Earth.

 20

You stand on a bathroom scale in an elevator accelerating upwards and it reads 200 Newtons. Which of the following is true?

You weigh 200 Newtons.

The scale exert a 200 N force on you.

The acceleration of the elevator is 20.4 m/s^2.

None of the above are correct.

 21

During the investigation of a traffic accident, police find skid marks 90 m long. They determine the coefficient of friction between the car's tires and the roadway to be 0.5 for the prevailing conditions. To find the speed of the car you must

know the mass of the car.

find the acceleration of the car.

know the mass of the car and find the acceleration of the car.

 22

An object moves left to right (right is positive) with speed decreasing at a constant rate and

its acceleration is positive.

the net force on it is decreasing.

the net force on it is increasing.

its acceleration is negative.

 23

Money is to wealth as

weight is to (the force of) gravity.

weight is to mass.

mass is to inertia.

gravity is to mass.

 24

A car pulls on a rope tied to a tree with a force of 1000 Newtons. Which of the following is not true.

The rope pulls on the tree with a force of 1000 Newtons.

The tree pulls on the rope with a force of 1000 Newtons.

The tension in the rope is 2000 Newtons.

The tension in the rope is 1000 Newtons.

 25

A 5 kg block and a 10 kg block slide down a frictionless incline and

they both have the same acceleration.

the 5 kg block has an acceleration of twice that of the 10 kg block.

the 10 kg block has an acceleration of twice that of the 5 kg block.

their acceleration depends on the normal force.