WOE - Work and Kinetic Energy

Work and Kinetic Energy

In physics, work occurs when a force is applied and motion occurs in the direction of the force. Work is a form of energy transfer.

As force is applied energy is transferred from the source of the force to the object the force is applied to. If the work causes only a change in motion, then work is equal to the change in kinetic energy.

This relationship is called the Work-Kinetic Energy Theorem and directly relates to the definition of kinetic energy. Kinetic energy relates directly the mass of the object and the velocity of the object squared.

Please watch the following presentation that will discuss Work, Kinetic Energy, and the Work-Kinetic Energy Theorem. 

Work and Kinetic Energy Practice

We will now practice solving problems using the concepts you learned in the presentation. Make sure that you show all your work when you solve your problems. The presentation will give you time to work through the problems, find a solution, and check your work.

Work and Kinetic Energy Self-Assessment

Now it is your turn. Complete the self-assessment questions to verify that you can apply the concepts of Work, Kinetic Energy, and the Work-Kinetic Energy Theorem.

1. A 15 kg box is pushed across a floor at constant velocity by a force of 10N directed at an angle of 25^o below the horizontal.
   1. How much work is done by the applied force as the box moves 12m?
   2. How much work is done by the force of friction as the box moves 12m? 
   3. How much work is done by gravity as the box moves 12m? 

SOLUTIONS Links to an external site.

2. The graph below shows the x component of force as it varies with the displacement x on a 5kg object.

1. How much work is done from x=0m to x=6m? 
2. How much work is done from x=6m to x= 12m? 
3. How much work is done from x=12m to x=22m? 
4. If the object starts with a velocity of 7 m/s, what is its velocity at x=6m, x=12m, and x=22m? 

SOLUTIONS Links to an external site.

3. 3. A 0.900 kg point mass is traveling at 2.00m/s when a variable force is applied to it. The force is a function of the displacement as indicated in the equation below. 

$F\left(x\right)=\sin2x+\cos x$

1. What is the work done on the particle from x=0m to x=15m?
2. What is the final velocity of the particle? 

SOLUTIONS Links to an external site.

Work and Kinetic Energy Practice Problems

Download Work and Kinetic Energy Practice Problems Links to an external site. for more practice. 

Download solutions Links to an external site. to the practice problems. 

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