Question 1

Daisy raises 10.Kg to a height of 2.5 meters in 2.0 seconds.
(a) How much work did she do?
(b) How much power was expended?
(c) If she raises it in 1.0 s rather than 2.0 s, how do the work and power change?

Accepted Answer

The answer of Daisy raises 10.Kg to a height of...

Question 2

An object of mass 10.0 kg is released from the top of an inclined plane which makes an angle of inclination of 30.0° with the horizontal. The object slides along the inclined plane. The questions refer to the instant when the object has traveled through a distance of 2.00 m measured along the slope. The coefficient of kinetic friction between the mass and the surface is 0.200. Use g = 10.0 m/s². (a) How much work is done by the net force on the mass? (b) How much work is done by the force of friction?

Accepted Answer

The answer of An object of mass 10.0 kg is...

Question 3

As plant engineer, Donna purchases an electrical motor which has an output of 1500. hp. If it requires 1.20 Megawatts of electricity, what is the efficiency of the motor?

Accepted Answer

The answer of As plant engineer, Donna purchases an electrical...

Question 4

FIGURE 7-2 Three applied forces, FS1U1B11S1U1B0 = 20.0 N, FS1U1B12S1U1B0 = 40.0 N, and FS1U1B13S1U1B0 = 10.0 N act on an object with a mass of 2.00 kg which can move along an inclined plane as shown in the figure. The questions refer to the instant when the object has moved 0.600 m along the surface of the inclined plane in the upward direction. Neglect friction and use g = 10.0 m/sS1U1P12S1S1P0. -Refer to Figure 7-2. What is the amount of work done by force F₁ as the object moves up the inclined plane?

Accepted Answer

The answer of FIGURE 7-2  Three applied forces, FS1U1B11S1U1B0...

Question 5

An airplane flies 160 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 by the air on the plane?

Accepted Answer

The work done by the air on the plane is negative because the force due to the air is in the opposite direction to the displacement of the plane. The magnitude of the work done is:$$W = Fd\cos	heta = (2.40	ext{ kN})(160	ext{ km})(10^3	ext{ m/km})\cos(180\degree + 10.0\degree + 30.0\degree) = -3.61	imes10^8	ext{ J}$$

Question 6

FIGURE 7-2 Three applied forces, FS1U1B11S1U1B0 = 20.0 N, FS1U1B12S1U1B0 = 40.0 N, and FS1U1B13S1U1B0 = 10.0 N act on an object with a mass of 2.00 kg which can move along an inclined plane as shown in the figure. The questions refer to the instant when the object has moved 0.600 m along the surface of the inclined plane in the upward direction. Neglect friction and use g = 10.0 m/sS1U1P12S1S1P0. -Refer to Figure 7-2. What is the amount of work done by force F₂ as the object moves up the inclined plane?

Accepted Answer

The answer of FIGURE 7-2  Three applied forces, FS1U1B11S1U1B0...

Question 7

How many joules of energy are used by a 2.0 hp motor that runs for 1.0 hr?

Accepted Answer

The answer of How many joules of energy are used...

Question 8

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?

Accepted Answer

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

Question 9

FIGURE 7-3 
-An object of mass = 2 kg is pulled by a constant force F = 4 N for a horizontal distance of 2 m. (Refer to Figure 7-3.) What is the work done along the +x-axis? Neglect friction.

Accepted Answer

The answer of FIGURE 7-3 
-An object of mass =...

Question 10

FIGURE 7-4  A constant force of 100 N is applied to a mass of 40.0 kg as shown in Figure 7-4. The force causes a displacement of 20.0 m to this mass along the + x-axis. Neglect friction.
-What is the work done by the component of the force in Figure 7-4 along the + y-axis?

Accepted Answer

The applied force is only in the +x direction and there is no displacement in the +y direction, so the work done by the component of the force in the +y direction is zero.

Question 11

A horizontal force of 40 N pushes an object of mass 5.0 kg up an inclined plane through a distance of 1.6 m measured along the plane. The plane is inclined at an angle of 30° to the horizontal. Neglect friction and use g = 10 m/s². (a) What is the work done by the horizontal force on the object? (b) What is the work done by the net force on the object? (c) What is the work done by the normal force on the object?

Accepted Answer

The answer of A horizontal force of 40 N pushes...

Question 12

An object of mass 10.0 kg is released from the top of an inclined plane which makes an angle of inclination of 30.0° with the horizontal. The object slides along the inclined plane. The questions refer to the instant when the object has traveled through a distance of 2.00 m measured along the slope. The coefficient of kinetic friction between the mass and the surface is 0.200. Use g = 10 m/s². How much work is done by gravity?

Accepted Answer

The work done by gravity is calculated using the formula: Work = m * g * d * sin(θ). Substituting the given values: Work = 10 kg * 10 m/s² * 2 m * sin(30°) = 100 J.

Question 13

FIGURE 7-4  A constant force of 100 N is applied to a mass of 40.0 kg as shown in Figure 7-4. The force causes a displacement of 20.0 m to this mass along the + x-axis. Neglect friction.
-What is the work done by the component of the force in Figure 7-4 along the +x-axis?

Accepted Answer

The answer of FIGURE 7-4  A constant force of...

Question 14

An object of 1.0 kg mass is pulled up an inclined plane by a constant force of 10 N that causes a displacement of 0.50 m. The angle of inclination with the horizontal is 30°. Neglect friction and use g = 10 m/s². What is the work done by the net force on the object along the inclined plane?

Accepted Answer

The answer of An object of 1.0 kg mass is...

Question 15

I left five 100. watt bulbs burning in my basement for two weeks. If electricity costs me 10.¢/kw-h, how much did the electricity cost (to the nearest dollar) to leave these bulbs on and how many Joules of electrical energy did they consume?

Accepted Answer

The answer of I left five 100. watt bulbs burning...

Question 16

Lisa runs up 4 flights of stairs in 22. seconds. She weighs 510. Newtons. If each flight rises 310. cm:
(a) What is her change in potential?
(b) What average power (watts) was required during the 22. s?
(c) What minimum horsepower motor would be required to do this?

Accepted Answer

The answer of Lisa runs up 4 flights of stairs...

Question 17

An object of 1.0 kg mass is pulled up an inclined plane by a constant force of 10 N that causes a displacement of 0.50 m. The angle of inclination with the horizontal is 30°. Neglect friction and use g = 10 m/s². What is the work done by the 10 N force on the object along the inclined plane?

Accepted Answer

The work done by a constant force is given by the formula W = Fd cos(θ), where F is the force magnitude, d is the displacement magnitude, and θ is the angle between F and d. In this problem, the force is 10 N, the displacement is 0.50 m along the inclined plane, and the angle between them is 30°. Therefore, the work done by the force is:

W = 10 N * 0.50 m * cos(30°) = 5.0 J

(Note that the mass is not needed to calculate the work done here, because it is not a factor in the formula for work done by a constant force.)

Question 18

A constant force of 20 N is applied to an object of mass 8.0 kg at an angle of 25° with the horizontal. What is the work done by this force on the object if it causes a displacement of 2.0 m along the horizontal direction?

Accepted Answer

The horizontal component of the applied force (20 N) is given by:
Fh = F cosθ = (20 N) cos(25°) ≈ 18.2 N

The work done by this horizontal force on the object is given by:
W = Fh d cosφ, where d is the displacement along the horizontal direction and φ is the angle between the force and the displacement.

Since the force and the displacement are both along the horizontal direction, we have φ = 0, so cosφ = 1.

Substituting the values, we get:
W = (18.2 N)(2.0 m)(1) = 36.4 J ≈ 36 J

Therefore, the answer is (C) 36 J.

Question 19

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?

Accepted Answer

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

Question 20

FIGURE 7-2 Three applied forces, FS1U1B11S1U1B0 = 20.0 N, FS1U1B12S1U1B0 = 40.0 N, and FS1U1B13S1U1B0 = 10.0 N act on an object with a mass of 2.00 kg which can move along an inclined plane as shown in the figure. The questions refer to the instant when the object has moved 0.600 m along the surface of the inclined plane in the upward direction. Neglect friction and use g = 10.0 m/sS1U1P12S1S1P0. -Refer to Figure 7-2. What is the amount of work done by the force F₃ as the object moves up the inclined plane?

Accepted Answer

The work done by a force is calculated as the component of the force in the direction of displacement times the displacement. If F3 is perpendicular to the direction of motion (up the incline), then the work done by F3 is zero.

Quiz 7: Work and Kinetic Energy

Daisy raises 10.Kg to a height of 2.5 meters in 2.0 seconds. (a) How much work did she do? (b) How much power was expended? (c) If she raises it in 1.0 s rather than 2.0 s, how do the work and power change?

As plant engineer, Donna purchases an electrical motor which has an output of 1500. hp. If it requires 1.20 Megawatts of electricity, what is the efficiency of the motor?

An airplane flies 160 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 by the air on the plane?

How many joules of energy are used by a 2.0 hp motor that runs for 1.0 hr?

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?

FIGURE 7-3 -An object of mass = 2 kg is pulled by a constant force F = 4 N for a horizontal distance of 2 m. (Refer to Figure 7-3.) What is the work done along the +x-axis? Neglect friction.

FIGURE 7-4 A constant force of 100 N is applied to a mass of 40.0 kg as shown in Figure 7-4. The force causes a displacement of 20.0 m to this mass along the + x-axis. Neglect friction. -What is the work done by the component of the force in Figure 7-4 along the + y-axis?

FIGURE 7-4 A constant force of 100 N is applied to a mass of 40.0 kg as shown in Figure 7-4. The force causes a displacement of 20.0 m to this mass along the + x-axis. Neglect friction. -What is the work done by the component of the force in Figure 7-4 along the +x-axis?

An object of 1.0 kg mass is pulled up an inclined plane by a constant force of 10 N that causes a displacement of 0.50 m. The angle of inclination with the horizontal is 30°. Neglect friction and use g = 10 m/s2. What is the work done by the net force on the object along the inclined plane?

I left five 100. watt bulbs burning in my basement for two weeks. If electricity costs me 10.¢/kw-h, how much did the electricity cost (to the nearest dollar) to leave these bulbs on and how many Joules of electrical energy did they consume?

Lisa runs up 4 flights of stairs in 22. seconds. She weighs 510. Newtons. If each flight rises 310. cm: (a) What is her change in potential? (b) What average power (watts) was required during the 22. s? (c) What minimum horsepower motor would be required to do this?

An object of 1.0 kg mass is pulled up an inclined plane by a constant force of 10 N that causes a displacement of 0.50 m. The angle of inclination with the horizontal is 30°. Neglect friction and use g = 10 m/s2. What is the work done by the 10 N force on the object along the inclined plane?

A constant force of 20 N is applied to an object of mass 8.0 kg at an angle of 25° with the horizontal. What is the work done by this force on the object if it causes a displacement of 2.0 m along the horizontal direction?

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?

An object of 1.0 kg mass is pulled up an inclined plane by a constant force of 10 N that causes a displacement of 0.50 m. The angle of inclination with the horizontal is 30°. Neglect friction and use g = 10 m/s². What is the work done by the net force on the object along the inclined plane?

An object of 1.0 kg mass is pulled up an inclined plane by a constant force of 10 N that causes a displacement of 0.50 m. The angle of inclination with the horizontal is 30°. Neglect friction and use g = 10 m/s². What is the work done by the 10 N force on the object along the inclined plane?