ENERGY What is it?. Where do you feel energy? Where do you see energy?

ENERGYWhat is it?

Where do you feel energy?

Where do you see energy?

Can energy be contained in things?

We usually observe energy when it is

being transformed…Energy can change from one form into

another form.

Hydro energy from a dam can be converted to

electrical energy.

Plutonium fuel rods in a nuclear power plant havestored energy that can betransformed into thermal

energy.

Solar energy can be transformed into storedchemical energy in an apple. You eat the apple and your body transforms that stored energy

into heat and motion.

Energy from various forms can be harnessed and USED to do work.

Quite simply, energy is something that allows us to do work!

What is work?Work is done when we lift a load against Earth’s gravity.

To do work on a barbell, the barbellmust be moved a distance.

Work = force x distanceW = Fd

(Nm = joule)

Is this guy doing work???

Which of these athletes are doing

work?

POWERWhat is the difference

between a person that runs up a flight of

stairs in 5 seconds versus 1 minute?

Power is a measure of how fast work is done.

Using a liter of gas, a Ford Mustang produces 50 units of power

for a half hour.

Using a liter of gas, a Boeing 747produces 90,000 units of power

for one second.

What makes a car engine more powerful?

Same amount of work, less time!!

Power = work time

Unit = Joule second = Watt

What are the basic forms of energy?

Kinetic energy = energy of motion

Potential energy = stored energy

KE = ½ mv2

PE = mgh How does this equationrelate to work?

These 2 forms of energy make up what we call “MECHANICAL ENERGY”

1. At which points or points (1...5) in the pendulum's swing is its KE greatest?Why?

2. At which points or points (1...5) in the pendulum's swing is its PE greatest?

3. How does the pendulum’s total energy (KE + PE) change?? Assume no friction.

Which picture shows the most WORK being done to lift the 10 N ball 3 m?