Tuesday, February 14th

Happy Valentines Day!

Bell Work

• Draw a Transverse Wave and label its crest, trough, amplitude, and wavelength.

Tuesday, February 14th

Happy Valentines Day!Kinetic Energy & Potential Energy

Goals for Today:

• Content Objective: given an object’s mass and velocity, and the equation for Kinetic Energy, you will be able to calculate the object’s KE using THE 4 STPES!

• Literacy Objective: You will be able to define kinetic energy and give an example of an object that has some.

Does the Ball have Energy?

• When I hold the baseball, does it have energy?

• When I drop it, does it have energy when it is falling?

• What about when it hits the ground?• Where did that energy come from?

The Baseball had 2 Types of Energy

• Potential Energy – stored energy, due to position (above the ground) or condition

• Kinetic Energy - energy a moving object has because of its motion

• When did the ball have Potential Energy?• When did it have Kinetic Energy?

Kinetic Energy

• All moving objects have Kinetic Energy• A moving car, a thrown javelin, a rolling

bowling ball, a running horse, someone riding a dirt bike

• We can calculate the amount of kinetic energy a moving object has using the equation:

KE = ½ * mass * velocity2

KE = ½ m v2

KE = ½ * mass * velocity2

• Kinetic Energy depends on:– MASS– VELOCITY

• Kinetic Energy is measured in Joules– “ J ” for short

I’ll use THE 4 STEPS to solve for KE:

• A person riding a dirt bike is traveling at 15 m/s. The weight of the bike and the person total 140 kg. What is their Kinetic Energy (KE)?

• Step 1. What Information are we given?• Step 2. What information do we need?• Step 3. What equation will we use?• Step 4. Insert Info and Solve.

KE = ½ m v2

Now let’s try Together

• A horse is walking around, grazing. He weighs 520 kg and is moving at 2 m/s. What is it’s Kinetic Energy?

• Step 1. What Information are we given?• Step 2. What information do we need?• Step 3. What equation will we use?• Step 4. Insert Info and Solve.

Try one in your Groups• You are target shooting, using 9 mm bullets.

The bullets weigh 0.115 kg and travel at a velocity of 340 m/s once they’re shot. What is this moving bullet’s Kinetic Energy?

• Step 1. What Information are we given?• Step 2. What information do we need?• Step 3. What equation will we use?• Step 4. Insert Info and Solve.

On Your Slip of Paper

• 1. Please define Kinetic Energy. Give an example of an object that has Kinetic Energy.

• 2. Using THE 4 STEPS, find the Kinetic Energy of a school bus with mass 10,000 kg if it is traveling down Beavercreek Road at 20 meters/second?

• --When You Are Done: Flip Paper Over, Remain Quiet, and Relax

A Couple Energy Jokes

• Why did the Gardner plant a light bulb?• He hoped to grow a Power Plant!• For this one, know that electricity is

measured in a unit called a “Watt”• As Seen on a Sign off Hwy 213:–You Can Trust Our Electricians, We Know

Watts Watt.

We Already Introduced Potential Energy, but let’s refresh our brains:

• Potential Energy – stored energy, due to position (above the ground) or condition

• I’ve found the man with the MOST Potential Energy – a type of energy called Gravitational Potential Energy

• http://www.youtube.com/watch?v=e335kbl9YWc&feature=player_embedded

Gravitational Potential Energy

• Today we are going to be talking about a type of Potential energy called Gravitational Potential Energy

• Gravitational Potential Energy – stored energy by objects due to their position above Earth’s surface

Gravitational Potential Energy

• Anything that can fall has stored energy• Amount of Potential Energy depends on:– The object’s mass – How high above the Earth’s surface it is (height)

• The equation for GPE GPE= mass *gravity * height

GPE = mgh

Climber Man’s GPE

• GPE = mass * gravity * height• Let’s Say he weighs 160lbs, which = 80 kg• Gravity is always 9.8 m/s/s• Climber man stood at 1,768 feet at the top.

1,768 ft = 540 meters• GPE = mass * gravity * height• GPE = (80kg)(9.8 m/s/s)(540m)• GPE = 423,360 J

What does 423,360 J really mean?

• If Climber Man fell into a 10,000 gallon pool, his 423,360 J would be able to instantly raise the temperature of the 10,000 gallons by 1 degree C!

Comparing Object’s GPE

• Let’s compare one student sitting on a stool.• To one student sitting on a text book. • Let’s assume the students have about the

same mass• Who has more Gravitational Potential Energy?

Another Comparison

• A hiker just summitted Mt. Hood, which stands about 11,000 feet tall. He stands proudly on the snowy mountain ground and poses for a picture.

• A second hiker, starting her journey, pulls over in Government Camp and stands on dry, snow-less pavement planning her hike on her map.

• Which of the two hikers has more Gravitational Potential Energy?

Other Side of your Slip of Paper

• A can of Monster Energy drink is sitting on the top shelf in your refrigerator. Two shelves below is a can of Mountain Dew.

• Which of the two energy-filled drinks has the most Gravitational Potential Energy.

• Why?