Work and Energy intro

When does work happen?

• When force causes an object to move or be displaced

• When you study for your Physics test

• Every time you apply force

• Alway

What is needed in order for work to be done?

• acceleration

• velocity

• mass

• movement at a constant speed

What is the unit for work?

• Newton

• Newton-meter

• Joule

What is a Joule equal to?

• Newton*meter

• meter per second squared

• kilometer per hour

• kilogram-meter squared per second squared

Would work be done if she held the box for a really long time?

• Yes because it would get really tiring to hold the box up for a long time

• No, because Physics is really mean, and doesn't care how tired her arms get

Can you ever do less than zero work?

• Yes, when the force is opposite to the direction of motion

• Yes, when you drop the object

• No, work is always positive.  That's why we whistle while we work.

• No, it is conceptually impossible to do less than zero work.

When is no work done?

• When motion is perpendicular to force

• When motion is parallel to force

• So many sarcastic responses came to mind that I couldn't choose one...

Why did she say we're addressing mechanical energy?

• She made a mistake

• Because work and energy are closely related

• She didn't.  You heard wrong.

The work done by friction

• Is positive

• Is negative

• Is called air resistance

She listed electrical, solar, wind, and hydro energy.  What kind(s) of energy did she leave out?

• Nuclear

• Chemical

• Thermal

• Sound

• All of the above, plus more.