Question 1

You stand on a spring scale on the floor of an elevator.Of the following, the scale shows the highest reading when the elevator:

Accepted Answer

A) moves upward with increasing speed 
B) moves upward with decreasing speed 
C) remains stationary 
D) moves downward with increasing speed 
E) moves downward at constant speed 
A) moves upward with increasing speed 
B) moves upward with decreasing speed 
C) remains stationary 
D) moves downward with increasing speed 
E) moves downward at constant speed

Question 2

Two blocks are connected by a massless string that passes over a massless pulley, as shown.In the absence of friction, how does the tension force exerted by the string on the 250 N block compare with the tension force exerted by the string on the 350 N block?

Accepted Answer

A) The force on the 250 N block is smaller by a factor of 0.71. 
B) The force on the 250 N block is larger by a factor of 1.4. 
C) The force on the 250 N block is always equal to its weight. 
D) The force on the 250 N block is equal to the weight of the 350 N block. 
E) The two forces are equal. 
A) The force on the 250 N block is smaller by a factor of 0.71. 
B) The force on the 250 N block is larger by a factor of 1.4. 
C) The force on the 250 N block is always equal to its weight. 
D) The force on the 250 N block is equal to the weight of the 350 N block. 
E) The two forces are equal.

Question 3

A car drives in a straight line on a level road with a constant acceleration of 3 m/s2.A ball is suspended by a string from the ceiling of the car; the ball does not swing, being at rest with respect to the car.What angle does the string make with the vertical?

Accepted Answer

A) 17$\degree$ 
B) 35$\degree$ 
C) 52$\degree$ 
D) 73$\degree$ 
E) Cannot be found without knowing the length of the string 
A) 17$\degree$ 
B) 35$\degree$ 
C) 52$\degree$ 
D) 73$\degree$ 
E) Cannot be found without knowing the length of the string

Question 4

Two blocks with masses m and M are pushed along a horizontal frictionless surface by a horizontal applied force as shown.The magnitude of the force of either of these blocks on the other is:

Accepted Answer

A) mF/(m + M) 
B) mF/M 
C) mF/(M - m) 
D) MF/(M + m) 
E) MF/m 
A) mF/(m + M) 
B) mF/M 
C) mF/(M - m) 
D) MF/(M + m) 
E) MF/m

Question 5

A 5-kg concrete block is lowered with a downward acceleration of 2.8 m/s2 by means of a rope.The force of the block on the rope is:

Accepted Answer

A) 14 N, up 
B) 14 N, down 
C) 35 N, up 
D) 35 N, down 
E) 49 N, up 
A) 14 N, up 
B) 14 N, down 
C) 35 N, up 
D) 35 N, down 
E) 49 N, up

Question 6

The unit of force called the newton is:

Accepted Answer

A) the force needed to accelerate a mass of 1 kg at a rate of 9.8 m/s2 
B) the force needed to accelerate a mass of 1 kg at a rate of 1 m/s2 
C) defined by means of Newton's third law 
D) 1 kg of mass 
E) 1 kg of force 
A) the force needed to accelerate a mass of 1 kg at a rate of 9.8 m/s2 
B) the force needed to accelerate a mass of 1 kg at a rate of 1 m/s2 
C) defined by means of Newton's third law 
D) 1 kg of mass 
E) 1 kg of force

Question 7

When a 40-N force, parallel to the incline and directed up the incline, is applied to a crate on a frictionless incline that is 30$\degree$ above the horizontal, the acceleration of the crate is 2.0 m/s2, up the incline.The mass of the crate is:

Accepted Answer

A) 3.8 kg 
B) 4.1 kg 
C) 5.8 kg 
D) 6.2 kg 
E) 10 kg 
A) 3.8 kg 
B) 4.1 kg 
C) 5.8 kg 
D) 6.2 kg 
E) 10 kg

Question 8

In general, any surface exerts two forces on objects that are in contact with it.One force is parallel to the surface and the other is perpendicular to the surface.What are these forces called?

Accepted Answer

A) The parallel force is surface tension and the perpendicular force is friction. 
B) The parallel force is the normal force and the perpendicular force is friction. 
C) The parallel force is friction and the perpendicular force is surface tension. 
D) The parallel force is friction and the perpendicular force is the normal force. 
E) The parallel force is static friction and the perpendicular force is kinetic friction. 
A) The parallel force is surface tension and the perpendicular force is friction. 
B) The parallel force is the normal force and the perpendicular force is friction. 
C) The parallel force is friction and the perpendicular force is surface tension. 
D) The parallel force is friction and the perpendicular force is the normal force. 
E) The parallel force is static friction and the perpendicular force is kinetic friction.

Question 9

A heavy wooden block is dragged by a force along a rough steel plate, as shown below for two cases.The magnitude of the applied force is the same for both cases.The normal force in (ii), as compared with the normal force in (i)is:

Accepted Answer

A) the same 
B) greater 
C) less 
D) less for some angles of the incline and greater for others 
E) less or greater, depending on the magnitude of the applied force 
A) the same 
B) greater 
C) less 
D) less for some angles of the incline and greater for others 
E) less or greater, depending on the magnitude of the applied force

Question 10

Equal forces act on isolated bodies A and B.The mass of B is three times that of A.The magnitude of the acceleration of A is:

Accepted Answer

A) three times that of B 
B) 1/3 that of B 
C) the same as B 
D) nine times that of B 
E) 1/9 that of B 
A) three times that of B 
B) 1/3 that of B 
C) the same as B 
D) nine times that of B 
E) 1/9 that of B

Question 11

A lead block is suspended from your hand by a string.The reaction to the force of gravity on the block is the force exerted by the:

Accepted Answer

A) string on the block 
B) block on the string 
C) string on the hand 
D) hand on the string 
E) block on the Earth 
A) string on the block 
B) block on the string 
C) string on the hand 
D) hand on the string 
E) block on the Earth

Question 12

A sled is on an icy (frictionless)slope that is 30$\degree$ above the horizontal.When a 40-N force, parallel to the incline and directed up the incline, is applied to the sled, the acceleration of the sled is 2.0 m/s2, down the incline.The mass of the sled is:

Accepted Answer

A) 4.1 kg 
B) 6.2 kg 
C) 8.1 kg 
D) 10 kg 
E) 14 kg 
A) 4.1 kg 
B) 6.2 kg 
C) 8.1 kg 
D) 10 kg 
E) 14 kg

Question 13

A man weighing 700 N is in an elevator that is accelerating upward at 4 m/s2.The force exerted on him by the elevator floor is:

Accepted Answer

A) 71 N 
B) 290 N 
C) 410 N 
D) 700 N 
E) 990 N 
A) 71 N 
B) 290 N 
C) 410 N 
D) 700 N 
E) 990 N

Question 14

A 70-N block and a 35-N block are connected by a string as shown.If the pulley is massless and the surface is frictionless, the magnitude of the acceleration of the 35-N block is:

Accepted Answer

A) 1.6 m/s2 
B) 3.3 m/s2 
C) 4.9 m/s2 
D) 6.5 m/s2 
E) 9.8 m/s2 
A) 1.6 m/s2 
B) 3.3 m/s2 
C) 4.9 m/s2 
D) 6.5 m/s2 
E) 9.8 m/s2

Question 15

The mass of a body:

Accepted Answer

A) is slightly different at different places on the Earth 
B) is a vector 
C) is independent of the acceleration due to gravity 
D) is the same for all bodies of the same volume 
E) can be measured most accurately on a spring scale 
A) is slightly different at different places on the Earth 
B) is a vector 
C) is independent of the acceleration due to gravity 
D) is the same for all bodies of the same volume 
E) can be measured most accurately on a spring scale

Question 16

In SI units a force is numerically equal to the ______, when the force is applied to it.

Accepted Answer

A) velocity of the standard kilogram 
B) speed of the standard kilogram 
C) velocity of any object 
D) acceleration of the standard kilogram 
E) acceleration of any object 
A) velocity of the standard kilogram 
B) speed of the standard kilogram 
C) velocity of any object 
D) acceleration of the standard kilogram 
E) acceleration of any object

Question 17

A 25-kg crate is pushed across a frictionless horizontal floor with a force of 20 N, directed 20$\degree$ below the horizontal.The acceleration of the crate is:

Accepted Answer

A) 0.27 m/s2 
B) 0.75 m/s2 
C) 0.80 m/s2 
D) 170 m/s2 
E) 470 m/s2 
A) 0.27 m/s2 
B) 0.75 m/s2 
C) 0.80 m/s2 
D) 170 m/s2 
E) 470 m/s2

Question 18

The block shown moves with constant velocity on a horizontal surface.Two of the forces on it are shown.A frictional force exerted by the surface is the only other horizontal force on the block.The frictional force is:

Accepted Answer

A) 0 N 
B) 2 N, leftward 
C) 2 N, rightward 
D) slightly more than 2 N, leftward 
E) slightly less than 2 N, leftward 
A) 0 N 
B) 2 N, leftward 
C) 2 N, rightward 
D) slightly more than 2 N, leftward 
E) slightly less than 2 N, leftward

Question 19

A heavy steel ball B is suspended by a cord from a block of wood W.The entire system is dropped through the air.Neglecting air resistance, the tension in the cord is:

Accepted Answer

A) zero 
B) the difference in the masses of B and W 
C) the difference in the weights of B and W 
D) the weight of B 
E) none of these 
A) zero 
B) the difference in the masses of B and W 
C) the difference in the weights of B and W 
D) the weight of B 
E) none of these

Question 20

A heavy ball is suspended as shown.A quick jerk on the lower string will break that string but a slow pull on the lower string will break the upper string.The first result occurs because:

Accepted Answer

A) the force is too small to move the ball 
B) action and reaction is operating 
C) the ball has inertia 
D) air friction holds the ball back 
E) the ball has too much energy 
A) the force is too small to move the ball 
B) action and reaction is operating 
C) the ball has inertia 
D) air friction holds the ball back 
E) the ball has too much energy

Exam 5: Force and Motion I

You stand on a spring scale on the floor of an elevator.Of the following, the scale shows the highest reading when the elevator:

Two blocks are connected by a massless string that passes over a massless pulley, as shown.In the absence of friction, how does the tension force exerted by the string on the 250 N block compare with the tension force exerted by the string on the 350 N block?

A car drives in a straight line on a level road with a constant acceleration of 3 m/s2.A ball is suspended by a string from the ceiling of the car; the ball does not swing, being at rest with respect to the car.What angle does the string make with the vertical?

Two blocks with masses m and M are pushed along a horizontal frictionless surface by a horizontal applied force as shown.The magnitude of the force of either of these blocks on the other is:

A 5-kg concrete block is lowered with a downward acceleration of 2.8 m/s2 by means of a rope.The force of the block on the rope is:

The unit of force called the newton is:

When a 40-N force, parallel to the incline and directed up the incline, is applied to a crate on a frictionless incline that is 30 °\degree° above the horizontal, the acceleration of the crate is 2.0 m/s2, up the incline.The mass of the crate is:

In general, any surface exerts two forces on objects that are in contact with it.One force is parallel to the surface and the other is perpendicular to the surface.What are these forces called?

A heavy wooden block is dragged by a force along a rough steel plate, as shown below for two cases.The magnitude of the applied force is the same for both cases.The normal force in (ii), as compared with the normal force in (i)is:

Equal forces act on isolated bodies A and B.The mass of B is three times that of A.The magnitude of the acceleration of A is:

A lead block is suspended from your hand by a string.The reaction to the force of gravity on the block is the force exerted by the:

A sled is on an icy (frictionless)slope that is 30 °\degree° above the horizontal.When a 40-N force, parallel to the incline and directed up the incline, is applied to the sled, the acceleration of the sled is 2.0 m/s2, down the incline.The mass of the sled is:

A man weighing 700 N is in an elevator that is accelerating upward at 4 m/s2.The force exerted on him by the elevator floor is:

A 70-N block and a 35-N block are connected by a string as shown.If the pulley is massless and the surface is frictionless, the magnitude of the acceleration of the 35-N block is:

The mass of a body:

In SI units a force is numerically equal to the ______, when the force is applied to it.

A 25-kg crate is pushed across a frictionless horizontal floor with a force of 20 N, directed 20 °\degree° below the horizontal.The acceleration of the crate is:

The block shown moves with constant velocity on a horizontal surface.Two of the forces on it are shown.A frictional force exerted by the surface is the only other horizontal force on the block.The frictional force is:

A heavy steel ball B is suspended by a cord from a block of wood W.The entire system is dropped through the air.Neglecting air resistance, the tension in the cord is:

A heavy ball is suspended as shown.A quick jerk on the lower string will break that string but a slow pull on the lower string will break the upper string.The first result occurs because:

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A car drives in a straight line on a level road with a constant acceleration of 3 m/s².A ball is suspended by a string from the ceiling of the car; the ball does not swing, being at rest with respect to the car.What angle does the string make with the vertical?

A 5-kg concrete block is lowered with a downward acceleration of 2.8 m/s² by means of a rope.The force of the block on the rope is:

When a 40-N force, parallel to the incline and directed up the incline, is applied to a crate on a frictionless incline that is 30 $\degree$ above the horizontal, the acceleration of the crate is 2.0 m/s², up the incline.The mass of the crate is:

A sled is on an icy (frictionless)slope that is 30 $\degree$ above the horizontal.When a 40-N force, parallel to the incline and directed up the incline, is applied to the sled, the acceleration of the sled is 2.0 m/s², down the incline.The mass of the sled is:

A man weighing 700 N is in an elevator that is accelerating upward at 4 m/s².The force exerted on him by the elevator floor is:

A 25-kg crate is pushed across a frictionless horizontal floor with a force of 20 N, directed 20 $\degree$ below the horizontal.The acceleration of the crate is: