9. Work & Energy

Net Work & Work-Energy Theorem

9. Work & Energy

# Net Work & Work-Energy Theorem - Video Tutorials & Practice Problems

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concept

## Calculating Net Work

Video duration:

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2

Problem

ProblemYou pull a 3kg box on a flat surface. The coefficient of kinetic friction is 0.6. When you pull the box horizontally through a distance of 10m, it accelerates at 2m/s2. Find the net work on the box.

A

17.6 J

B

35.3 J

C

176.4 J

D

60 J

3

Problem

ProblemTo pull a 51 kg crate across a rough floor, a worker applies a force of 100 N, directed 37°above the horizontal. The coefficient of friction is 0.16. If the crate moves 3.0 m, what is the total work done on the crate?

A

29 J

B

0 J

C

240 J

D

169.6 J

4

concept

## The Work-Energy Theorem

Video duration:

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5

Problem

ProblemA box slides across the floor with an initial speed of 3.5m/s. If the coefficient of kinetic friction is 0.15, how far will the box slide before stopping completely?

A

1.19 m

B

4.17 m

C

9 m

D

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example

## Net Work & Constant Speed

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PRACTICE PROBLEMS AND ACTIVITIES (50)

- You throw a 3.00-N rock vertically into the air from ground level. You observe that when it is 15.0 m above th...
- A 1.50-kg book is sliding along a rough horizontal surface. At point A it is moving at 3.21 m/s, and at point ...
- You throw a 3.00-N rock vertically into the air from ground level. You observe that when it is 15.0 m above th...
- (II) An 85-g arrow is fired from a bow whose string exerts an average force of 105 N on the arrow over a dista...
- An 8.0 kg crate is pulled 5.0 m up a 30° incline by a rope angled 18 ° above the incline. The tension in the r...
- A 2.0 kg particle moving along the x-axis experiences the force shown in FIGURE EX9.22. The particle's velocit...
- A red ball has a mass of 250 g. A constant force pushes the red ball horizontally and launches it at a speed o...
- A pitcher accelerates a 150 g baseball from rest to 35 m/s. How much work does the pitcher do on the ball?
- A horizontal spring with spring constant 85 N/m extends outward from a wall just above floor level. A 1.5 kg b...
- A ball shot straight up with kinetic energy K₀ reaches height h. What height will it reach if the initial kine...
- A 55 kg softball player slides into second base, generating 950 J of thermal energy in her legs and the ground...
- A baggage handler throws a 15 kg suitcase along the floor of an airplane luggage compartment with a speed of 1...
- Justin, with a mass of 30 kg, is going down an 8.0-m-high water slide. He starts at rest, and his speed at the...
- A 50 kg ice skater is gliding along the ice, heading due north at 4.0 m/s. The ice has a small coefficient of ...
- A 737-800 jet airliner has twin engines, each with 105 kN thrust. A 78,000 kg jet reaches a takeoff speed of 7...
- A horizontal spring with spring constant 250 N/m is compressed by 12 cm and then used to launch a 250 g box ac...
- (a) How much work does an elevator motor do to lift a 1000 kg elevator a height of 100 m?
- Susan's 10 kg baby brother Paul sits on a mat. Susan pulls the mat across the floor using a rope that is angle...
- FIGURE EX9.20 is the force-versus-position graph for a particle moving along the x-axis. Determine the work do...
- A horizontal spring with spring constant 750 N/m is attached to a wall. An athlete presses against the free en...
- The cable of a crane is lifting a 750 kg girder. The girder increases its speed from 0.25 m/s to 0.75 m/s in a...
- A pile driver lifts a 250 kg weight and then lets it fall onto the end of a steel pipe that needs to be driven...
- CALC A 2.6 kg block is attached to a horizontal rope that exerts a variable force Fx=(20−5x) N, where x is in ...
- The maximum energy a bone can absorb without breaking is surprisingly small. Experimental data show that a leg...
- A 20 kg child is on a swing that hangs from 3.0-m-long chains. What is her maximum speed if she swings out to ...
- In a hydroelectric dam, water falls 25 m and then spins a turbine to generate electricity. (a) What is (delta)...
- A cable with 20.0 N of tension pulls straight up on a 1.50 kg block that is initially at rest. What is the blo...
- A 1500 kg car traveling at 10 m/s suddenly runs out of gas while approaching the valley shown in FIGURE EX10.1...
- A pendulum is made by tying a 500 g ball to a 75-cm-long string. The pendulum is pulled 30 degree to one side,...
- A 55 kg skateboarder wants to just make it to the upper edge of a 'quarter pipe,' a track that is one-quarter ...
- A system of two objects has (delta)Ktot = 7J and (delta)U = -5J. (a) How much work is done by interaction forc...
- (II) A 66.5-kg hiker starts at an elevation of 1150 m and climbs to the top of a peak 2660 m high.(c) Can the ...
- (II) A 66.5-kg hiker starts at an elevation of 1150 m and climbs to the top of a peak 2660 m high.(b) What is ...
- An airplane pilot fell 370 m after jumping from an aircraft without his parachute opening. He landed in a snow...
- Stretchable ropes are used to safely arrest the fall of rock climbers. Suppose one end of a rope with unstretc...
- An airplane pilot fell 370 m after jumping from an aircraft without his parachute opening. He landed in a snow...
- Stretchable ropes are used to safely arrest the fall of rock climbers. Suppose one end of a rope with unstretc...
- (II) How much work would be required to move a satellite of mass m from a circular orbit of radius r₁ = 2r_E a...
- A 25-g projectile is fired into a cube of ballistic gel at a velocity of 360 m/s. If the projectile penetrates...
- (II) A car traveling at a velocity v can stop in a minimum distance d. What would be the car’s minimum stoppin...
- (II) At an accident scene on a level road, investigators measure a car’s skid mark to be 78 m long. It was a r...
- (II) At an accident scene on a level road, investigators measure a car’s skid mark to be 78 m long. It was a r...
- (II) At an accident scene on a level road, investigators measure a car’s skid mark to be 78 m long. It was a r...
- II) A 1.60-m-tall person lifts a 1.65-kg book off the ground so it is 2.20 m above the ground. What is the pot...
- In the game of paintball, players use guns powered by pressurized gas to propel 33-g gel capsules filled with ...
- (II) A meteorite has a speed of 90.0 m/s when 750 km above the Earth. It is falling vertically (ignore air re...
- (II) A NASA satellite is said to have observed an asteroid that is on a collision course with the Earth. The a...
- We usually neglect the mass of a spring if it is small compared to the mass attached to it. But in some applic...
- (II) A 3.5-kg object moving in two dimensions initially has a velocity v₁→ (10.0 î + 20.0 ĵ) m/s. A net force ...
- A 2.0-kg block slides across a rough surface with a constant coefficient of kinetic friction of 0.50 (Fig. 7–3...