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Questions - PowerPoint PPT Presentation

Questions. What makes a light bulb light? What do some people have a lot of after eating or drinking something sugary? What do these two things have in common?. Energy. Is the ability to do work. Example: The tennis player does work on her racket by exerting force on it.

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Presentation Transcript

• What makes a light bulb light?

• What do some people have a lot of after eating or drinking something sugary?

• What do these two things have in common?

• Is the ability to do work.

• Example:

• The tennis player does work on her racket by exerting force on it.

• The racket does work on the ball.

• The ball does work on the net

• Is the energy of motion.

• Kinetic energy depends on mass and speed.

• The faster something is moving, the more kinetic energy it has.

• Also, the more mass a moving object has, the greater its kinetic energy.

• Is the energy an object has because of its position.

• Example:

• The bow has energy because work has been done to change its shape.

• Energy can be stored in bowstrings, springs, and rubber bands.

• You change the shape of these objects by stretching them.

• When you lift an object, you do work on it.

• You use a force that is against the force of gravity.

• Books on a shelf have gravitational potential energy.

• Before you eat that sugary drink or food, it has the potential to give you energy.

• Food and drinks have chemical potential energy due to their chemical composition.

An apple on a tree.

A rolling ball.

Potential or Kinetic?

A stretched rubber band.

Our food and drink.

Gravitational, Elastic, or Chemical?

A book on a shelf.

Gravitational, Elastic, or Chemical?

A stretched rubber band.

If Mr. Friel rolled a bowling ball and a soccer ball down the aisle at the same speed, which one would have more kinetic energy? Why?

A tennis ball rolling slow or a tennis ball rolling fast?

• Mass – A measure of how much matter is in an object

• Mass is not the same as size - some big things, like balloons, are very light, while some small things, like a gold brick, are very heavy. A truck would be the same size whether it was empty or full, but it would have a lot more mass if it was full - and it would be even harder to stop.

• Mass is commonly measured by how much something weighs. But weight can change depending on where you are (such as on the moon) while the mass stays the same.

• Weight – The downward force caused by gravity on an object.

• Weightcan change depending on where you are (such as on the moon) while the mass stays the same.

• Here are some conditions where the Weight might change:

in space (can be weightless!)

on the moon (a 100 kg mass would weigh 16.6 kg)

• An object's mass doesn't change (unless you remove some), but its weight can change.

• The force of attraction by which terrestrial bodies tend to fall toward the center of the earth.