work-energy+problems

= **Work-Energy** =

= =




 * Describe the difference between Kinetic Energy and Potential Energy. **

Potential Energy is the energy stored in a system. While, Kinetic Energy is energy that is possessed because of its motion.

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 * How does it relate to what we observed using the Xpult? **

The two types of energy relate to the X-pult because kinetic energy is the ball flying in the air (motion) after it is launched and potential energy is when the catapult is pulled back and has tension from the rubber bands creating energy that is stored in the system.


 * Work is the force used to move an object some distance **


 * W = F x d **


 * Force needed to lift the box = 100 Newtons **


 * Distance needed to lift the box = 2 meters **


 * 1) What work was needed to move the box 2 meters? **
 * ( Newtons•meters is considered a Joule) **

100 Newtons (Force) x 2 meters (Distance) = 200 Joules. The work needed to move the box was 200 Joules.

** Mechanical Advantage = Ouput force/ **** Input force **

** 2) The board is 12 meters long. The fulcrum is 3 meters from the Boulder and 9 meters from the person applying the force. A person applies a force of 5 newtons and the boulder is 15 Newtons. **



** What is the mechanical advantage? **

The mechanical advantage is 3 because 15N, the boulder, over 5N, the force exerted by the person, = 3 over 1.

__15N__ or __3__ 5N 1

This means the machine multiplies your effort 3X.

** What is the work being done by the Machine? **

The work being done by the machine is 45 Joules because the distance between the boulder and fulcrum is 3 meters and the boulder is 15 newtons. So, 3M x 15N = 45 Joules.

** What is the work being done by the person? **

The work being done by the person is 45 Joules because the distance between the person and the fulcrum is 9 meters and the person is applying a force of 5 newtons. So, 9M X 5N = 45 Joules.

** Compare the Work of the person and machine. **

The Work being done by the person and the machine is equal, they both add up to 45 Joules.

** Explain scientifically why the job is easier for the person and harder for the machine. (even though the work is the same). **

Scientifically, the job is easier for the person and harder for the machine. The person only applies a small amount fo effort (force) over a long distance. While, the machine has to apply a much greater effort over a short distance. Even though the work is the same, the machine has to exert much more effort than the person.