Question 1

A traffic light weighing 100 N is supported by two ropes as shown in the figure. The tensions in the ropes are closest to 
A) 50 N.
B) 56 N.
C) 63 N.
D) 66 N.
E) 83 N.

Accepted Answer

The answer of A traffic light weighing 100 N is...

Question 2

A 50.0-kg block is being pulled up a 16.0° slope by a force of 250 N which is parallel to the slope.The coefficient of kinetic friction between the block and the slope is 0.200.What is the magnitude of the acceleration of the block? A) 0.528 m/s² B) 0.158 m/s² C) 0.412 m/s² D) 0.983 m/s² E) 0.260 m/s²

Accepted Answer

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Question 3

An airplane flies 120 km at a constant altitude in a direction 30.0° north of east. A wind is blowing that results in a net horizontal force on the plane due to the air of 2.40 kN in a direction 10.0° south of west. How much work is done on the plane by the air? A) -2.71 × 10⁸ J B) -0.985 × 10⁸ J C) -221 × 10⁸ J D) 221 × 10⁸ J E) 0.821 × 10⁸ J

Accepted Answer

The work done by a force is given by the formula $W = Fd\cos(\theta)$, where $F$ is the magnitude of the force, $d$ is the distance over which the force acts, and $\theta$ is the angle between the force direction and the direction of motion. Here, the force is 2.40 kN (2400 N) and the distance is 120 km (120,000 m). The angle between the direction of the force (10° south of west) and the direction of the plane's motion (30° north of east) is 180° - (30° + 10°) = 140°. Thus, $W = 2400 \times 120,000 \times \cos(140°)$, which results in a negative value because the force is acting opposite to the direction of motion, indicating that the work done by the air on the plane is negative.

Question 4

In the figure,two boxes,each of mass 24 kg,are at rest and connected as shown.The coefficient of kinetic friction between the inclined surface and the box is 0.31.Find the speed of the boxes just after they have moved 1.6 m.

Accepted Answer

The answer of In the figure,two boxes,each of mass 24...

Question 5

The figure shows two forces,each of magnitude 4.6 N,acting on an object.The angle between these forces is 40°,and they make equal angles above and below the horizontal.What third force will cause the object to be in equilibrium (acceleration equals zero)? 
A) 8.6 N pointing to the right
B) 7.0 N pointing to the right
C) 4.3 N pointing to the right
D) 3.5 N pointing to the right

Accepted Answer

The answer of The figure shows two forces,each of magnitude...

Question 6

Find the net work done by friction on the body of a snake slithering in a complete circle of 3.93 m radius.The coefficient of friction between the ground and the snake is 0.25,and the snake's weight is
54)0 N.
A) -330 J
B) 0 J
C) -3300 J
D) -670 J

Accepted Answer

The net work done by friction can be found using the equation:
Work = Force x Distance x cos(theta)

Since the snake is slithering in a complete circle, the distance it travels is the circumference of the circle:
Distance = 2 x pi x radius
Distance = 2 x pi x 3.93 m
Distance = 24.7 m

The force of friction can be found using the equation:
Force of Friction = Coefficient of Friction x Normal Force

The normal force is equal to the weight of the snake:
Normal Force = 54.0 N

Force of Friction = 0.25 x 54.0 N
Force of Friction = 13.5 N

The angle between the force of friction and the distance moved is 180 degrees, so cos(theta) = -1.

Plugging in the values:
Work = 13.5 N x 24.7 m x -1
Work = -333.15 J

Therefore, the net work done by friction is approximately -330 J.

Question 7

A 200 g hockey puck is launched up a metal ramp that is inclined at a 30° angle.The coefficients of static and kinetic friction between the hockey puck and the metal ramp are μ_s = 0.40 and μ_k = 0.30,respectively.The puck's initial speed is 4.9 m/s.What speed does it have when it slides back down to its starting point? A) 2.8 m/s B) 3.5 m/s C) 4.2 m/s D) 4.9 m/s

Accepted Answer

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Question 8

A system of blocks and a frictionless pulley is shown in the figure.Block A has a mass of 2.0 kg and is on a rough horizontal surface for which μ_s = 0.40 between the surface and block A.The rope pulls horizontally on block A.Block C has a mass of 1.0 kg.An external force P = 23.0 N,applied vertically to block A,maintains the system at rest as shown in the figure.What is the friction force on block A? A) 6.3 N B) 6.9 N C) 7.5 N D) 5.7 N E) 5.1 N

Accepted Answer

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Question 9

In the figure,a 700-kg crate is on a rough surface inclined at 30°.A constant external force P = 5600 N is applied horizontally to the crate.As the force pushes the crate a distance of 3.00 m up the incline,the speed changes from 1.40 m/s to 2.50 m/s.How much work does gravity do on the crate during this process? 
A) -10,300 J
B) -3400 J
C) +10,300 J
D) +3400 J
E) zero

Accepted Answer

To find the work done by gravity on the crate, we need to find the change in potential energy. As the crate moves up the incline, its potential energy increases.

ΔPE = mgh

where m is the mass of the crate, g is the acceleration due to gravity, and h is the change in height. Since the crate only moves along the incline, we can use the component of gravity parallel to the incline.

mgh = mg sin θ * d = (700 kg) * (9.81 m/s²) * sin 30° * 3.00 m = 10,300 J

Since the angle between the force and displacement is not 0° or 180°, the work done by gravity is negative (i.e. gravity does negative work on the crate).

Therefore, the answer is A) -10,300 J.

Question 10

Three forces,F₁ = 20.0 N,F₂ = 40.0 N,and F₃ = 10.0 N act on an object with a mass of 2.00 kg which can move along a frictionless inclined plane as shown in the figure.The questions refer to the instant when the object has moved through a distance of 0.600 m along the surface of the inclined plane in the upward direction.Calculate the amount of work done by (a) F₁ (b) F₂ (c) F₃.

Accepted Answer

The answer of Three forces,F₁ = 20.0 N,F₂ = 40.0...

Question 11

A traveler pulls on a suitcase strap at an angle 36° above the horizontal.If 908 J of work are done by the strap while moving the suitcase a horizontal distance of 15 m,what is the tension in the strap?
A) 75 N
B) 61 N
C) 85 N
D) 92 N

Accepted Answer

The answer of A traveler pulls on a suitcase strap...

Question 12

A 4.00-kg block rests on a 30.0° incline as shown in the figure. If the coefficient of static friction between the block and the incline is 0.700,what magnitude horizontal force F must act on the block to start it moving up the incline? 
A) 34.0 N
B) 51.1 N
C) 54.7 N
D) 84.0 N
E) 76.4 N

Accepted Answer

First, we need to calculate the weight of the block that is acting perpendicular to the incline:

$W_{\perp}= mg\cos{	heta} = (4	ext{ kg})(9.81	ext{ m/s}^2)\cos{30^{\circ}} = 33.91	ext{ N}$

Next, we need to calculate the maximum force of static friction that is acting parallel to the incline:

$F_f= \mu_s W_{\perp} = (0.700)(33.91	ext{ N}) = 23.74	ext{ N}$

Finally, we need to find the minimum force required to start the block moving up the incline. This force must be greater than the force of static friction:

$F > F_f = 23.74	ext{ N}$

The only answer choice that satisfies this condition is D) 84.0 N.

Question 13

In the figure,a constant external force P = 160 N is applied to a 20.0-kg box,which is on a rough horizontal surface.While the force pushes the box a distance of 8.00 m,the speed changes from 0.500 m/s to 2.60 m/s.The work done by friction during this process is closest to 
A) -1040 J.
B) +1110 J.
C) +1170 J.
D) +1040 J.
E) -1170 J.

Accepted Answer

The answer of In the figure,a constant external force P...

Question 14

A box is sliding down an incline tilted at a 12.0° angle above horizontal. The box is initially sliding down the incline at a speed of 1.50 m/s. The coefficient of kinetic friction between the box and the incline is 0.340. How far does the box slide down the incline before coming to rest?
A) 0.920 m
B) 2.33 m
C) 1.78 m
D) 0.720 m
E) The box does not stop. It accelerates down the plane.

Accepted Answer

The answer of A box is sliding down an incline...

Question 15

Two blocks are connected by a string that goes over an ideal pulley as shown in the figure and pulls on block A parallel to the surface of the plane.Block A has a mass of 3.00 kg and can slide along a rough plane inclined 30.0° to the horizontal.The coefficient of static friction between block A and the plane is 0.400.What mass should block B have in order to start block A sliding up the plane?

Accepted Answer

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Question 16

A student slides her 80.0-kg desk across the level floor of her dormitory room a distance 4.00 m at constant speed. If the coefficient of kinetic friction between the desk and the floor is 0.400,how much work did she do?
A) 128 J
B) 3.14 kJ
C) 26.7 J
D) 1.26 kJ
E) 24.0 J

Accepted Answer

The answer of A student slides her 80.0-kg desk across...

Question 17

A 5.00-kg box slides 4.00 m across the floor before coming to rest. What is the coefficient of kinetic friction between the floor and the box if the box had an initial speed of 3.00 m/s?
A) 1.13
B) 0.587
C) 0.115
D) 0.229
E) 0.267

Accepted Answer

The answer of A 5.00-kg box slides 4.00 m across...

Question 18

Two blocks are connected by a string that goes over an ideal pulley as shown in the figure.Block A has a mass of 3.00 kg and can slide over a rough plane inclined 30.0° to the horizontal.The coefficient of kinetic friction between block A and the plane is 0.400.Block B has a mass of 2.77 kg.What is the acceleration of the blocks? A) 0.392 m/s² B) 1.96 m/s² C) 3.12 m/s² D) 5.35 m/s² E) 0.00 m/s²

Accepted Answer

The answer of Two blocks are connected by a string...

Question 19

The figure shows two forces acting at right angles on an object.They have magnitudes F₁ = 6.3 N and F₂ = 2.1 N. What third force will cause the object to be in equilibrium (acceleration equals zero)? A) 6.6 N at 162° counterclockwise from ₁ B) 6.6 N at 108° counterclockwise from ₁ C) 4.2 N at 162° counterclockwise from ₁ D) 4.2 N at 108° counterclockwise from ₁

Accepted Answer

The answer of The figure shows two forces acting at...

Question 20

A force  = 12 N 
- 10 N 
Acts on an object.How much work does this force do as the object moves from the origin to the point 
A) 46 J
B) 266 J
C) 37 J
D) 62 J

Accepted Answer

The answer of A force  = 12 N 
-...

Quiz 10: Motion in a Plane

A traffic light weighing 100 N is supported by two ropes as shown in the figure. The tensions in the ropes are closest to

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

An airplane flies 120 km at a constant altitude in a direction 30.0° north of east. A wind is blowing that results in a net horizontal force on the plane due to the air of 2.40 kN in a direction 10.0° south of west. How much work is done on the plane by the air?

In the figure,two boxes,each of mass 24 kg,are at rest and connected as shown.The coefficient of kinetic friction between the inclined surface and the box is 0.31.Find the speed of the boxes just after they have moved 1.6 m.

The figure shows two forces,each of magnitude 4.6 N,acting on an object.The angle between these forces is 40°,and they make equal angles above and below the horizontal.What third force will cause the object to be in equilibrium (acceleration equals zero) ?

Find the net work done by friction on the body of a snake slithering in a complete circle of 3.93 m radius.The coefficient of friction between the ground and the snake is 0.25,and the snake's weight is 54) 0 N.

A traveler pulls on a suitcase strap at an angle 36° above the horizontal.If 908 J of work are done by the strap while moving the suitcase a horizontal distance of 15 m,what is the tension in the strap?

A 4.00-kg block rests on a 30.0° incline as shown in the figure. If the coefficient of static friction between the block and the incline is 0.700,what magnitude horizontal force F must act on the block to start it moving up the incline?

In the figure,a constant external force P = 160 N is applied to a 20.0-kg box,which is on a rough horizontal surface.While the force pushes the box a distance of 8.00 m,the speed changes from 0.500 m/s to 2.60 m/s.The work done by friction during this process is closest to

A box is sliding down an incline tilted at a 12.0° angle above horizontal. The box is initially sliding down the incline at a speed of 1.50 m/s. The coefficient of kinetic friction between the box and the incline is 0.340. How far does the box slide down the incline before coming to rest?

A student slides her 80.0-kg desk across the level floor of her dormitory room a distance 4.00 m at constant speed. If the coefficient of kinetic friction between the desk and the floor is 0.400,how much work did she do?

A 5.00-kg box slides 4.00 m across the floor before coming to rest. What is the coefficient of kinetic friction between the floor and the box if the box had an initial speed of 3.00 m/s?

The figure shows two forces acting at right angles on an object.They have magnitudes F₁ = 6.3 N and F₂ = 2.1 N. What third force will cause the object to be in equilibrium (acceleration equals zero) ?

A force = 12 N - 10 N Acts on an object.How much work does this force do as the object moves from the origin to the point

Quiz 10: Motion in a Plane

A traffic light weighing 100 N is supported by two ropes as shown in the figure. The tensions in the ropes are closest to

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

An airplane flies 120 km at a constant altitude in a direction 30.0° north of east. A wind is blowing that results in a net horizontal force on the plane due to the air of 2.40 kN in a direction 10.0° south of west. How much work is done on the plane by the air?

In the figure,two boxes,each of mass 24 kg,are at rest and connected as shown.The coefficient of kinetic friction between the inclined surface and the box is 0.31.Find the speed of the boxes just after they have moved 1.6 m.

The figure shows two forces,each of magnitude 4.6 N,acting on an object.The angle between these forces is 40°,and they make equal angles above and below the horizontal.What third force will cause the object to be in equilibrium (acceleration equals zero) ?

Find the net work done by friction on the body of a snake slithering in a complete circle of 3.93 m radius.The coefficient of friction between the ground and the snake is 0.25,and the snake's weight is 54) 0 N.

A traveler pulls on a suitcase strap at an angle 36° above the horizontal.If 908 J of work are done by the strap while moving the suitcase a horizontal distance of 15 m,what is the tension in the strap?

A 4.00-kg block rests on a 30.0° incline as shown in the figure. If the coefficient of static friction between the block and the incline is 0.700,what magnitude horizontal force F must act on the block to start it moving up the incline?

In the figure,a constant external force P = 160 N is applied to a 20.0-kg box,which is on a rough horizontal surface.While the force pushes the box a distance of 8.00 m,the speed changes from 0.500 m/s to 2.60 m/s.The work done by friction during this process is closest to

A box is sliding down an incline tilted at a 12.0° angle above horizontal. The box is initially sliding down the incline at a speed of 1.50 m/s. The coefficient of kinetic friction between the box and the incline is 0.340. How far does the box slide down the incline before coming to rest?

A student slides her 80.0-kg desk across the level floor of her dormitory room a distance 4.00 m at constant speed. If the coefficient of kinetic friction between the desk and the floor is 0.400,how much work did she do?

A 5.00-kg box slides 4.00 m across the floor before coming to rest. What is the coefficient of kinetic friction between the floor and the box if the box had an initial speed of 3.00 m/s?

The figure shows two forces acting at right angles on an object.They have magnitudes F1 = 6.3 N and F2 = 2.1 N. What third force will cause the object to be in equilibrium (acceleration equals zero) ?

A force = 12 N - 10 N Acts on an object.How much work does this force do as the object moves from the origin to the point

The figure shows two forces acting at right angles on an object.They have magnitudes F₁ = 6.3 N and F₂ = 2.1 N. What third force will cause the object to be in equilibrium (acceleration equals zero) ?