Energy and Work Standard Essential Question: What is the relationship between energy and work?

Energy Energy is a property that enables something to do work. Where does the man get energy? We call this __________ energy. What is he doing with that energy? He is converting __________ energy to __________ energy to perform __________.

So, what is work? Work means to (1) apply a force to an object over a distance, and (2) the object moves in response to the force. Force X Distance=Work In other words, some force pushes or pulls on an object and if the object moves because of the force, then work has been done.

Evidence of Energy If something has the ability to cause a change in motion, it is has energy. What are the types of energy we have discussed? Energy can cause work to be done, so when we see work done, we see evidence of energy.

Examples When a toy car at rest is pushed, work is done on the car if it moves. This work (or movement) is evidence of energy.

Examples When a fan is connected to an electric circuit, and the switch is on, it moves, so work was done on the fan. This work (or movement) is evidence of energy.

Examples When an object is lifted, it moves, so work is done on the object. This work (or movement) is evidence of energy.

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Has work been performed? I push on the wall as hard as I can but the wall does not move. Has work been performed on the wall? I hold a glass of water in my hand and walk across the room. Has work been performed on the glass? I place the glass of water on the table. Has work been performed on the glass?

Answers and explanations 1.No work has been performed because even though I used a great deal of force the wall did not move. 2.No work has been performed because even though I moved my body across the room nothing happened to the glass of water other than it moved with me. Think about you riding in the car. Is work being performed on you or is work being performed on the car? 3.Yes work has been performed because a force (gravity) and my hand moved the glass down (a distance ) to the table.

Measuring Force A spring scale is used to measure force. Force (including weight (not mass)) is measured in SI (metric) units called newtons (N). We will use a spring scale in our next labs and make measurements using newtons (N). Answer to the essential question: The relationship between energy and work is that energy is needed in order for work to be performed.