6th Grade Science

Chapter 17 Energy and Resources

Notes Section

17.2

• What energy form is always produced in a energy transformation?

• Heat energy is always one of the products of an energy transformation.

• What is the law of conservation of energy?• Energy is not created or destroyed. It only

changes form.

Key Questions 1

Transforming Electrical Energy

Tracking Energy Transformations

• As a mountain biker pedals, leg muscles transform chemical energy into kinetic energy.

• The kinetic energy of his leg muscles transforms into kinetic energy of the bicycle as he pedals.

Energy Changes Form

• New types of cars use an electric motor along with a gasoline engine.

• These engines are more efficient so the car can travel farther on a gallon of gas.

Chevy Volt, Toyota Prius

• What happens to energy as an object rises and falls?• As an object rises and falls, kinetic and potential

energy are transformed into each other, but the total energy does not change.

• Which way does thermal energy travel?• Thermal energy only goes from something at a higher

temperature to something at a lower temperature.

Key Questions 2

The Tadpole Galaxy

This lady flipping pancakes demonstrates how potential and kinetic energy are transformed into each other but the total energy remains the same.

On a surprise visit to Belfast, both Prince William and fiancée Kate Middleton attempted the tricky pancake flip for a charity fundraiser to mark Shrove Tuesday - Pancake Day. William tossed his pancake with aplomb. After some practice Kate was tossing with ease.

One top fuel dragster 500 cubic inch Hemi engine (6,000 horsepower) makes more horsepower than the first 4 rows of stock cars at the Daytona 500.

Top fuel dragster vs. Z06 CorvetteImagine you are driving the Chevrolet Corvette Z06 twin-turbo 7.0-liter LS7 at 800 horsepower and $140,000. What if a top fuel dragster is staged and ready to launch down a quarter mile strip (440 yards)? You're doing 200, the dragster just starts the moment you pass him who will get to the ¼ mile finish line first?

The dragster launches and starts after you. The dragster will pass you in under 4 seconds doing more than 300 mph. The acceleration of the dragster has put 8 times the force of gravity on the driver. Nothing on land accelerates faster on land. The dragster crosses the finish line first with room to spare.

The dragster uses 1.1 gallons of nitro methane fuel per second as it goes down the track. Still, more than 80% of the fuel energy was lost to heat.

• What is a generator?• A generator is a device that transforms kinetic

energy into electrical energy. • What is a turbine?• A turbine is a set of narrowly spaced fan blades that

spin when steam is applied to it.

Key Questions 3

The Sombrero Galaxy

Steam Turbines change steam into kinetic energy. The rotating shaft powers a large generator that makes electricity

In a hydroelectric generator, water come in through the wicket gate and turns the turbine blades. The blades are connected to a shaft that turns an electric generator.

• How does a power plant generate electricity?• A power plant burns fossil fuels that boils water

to produce steam. Steam is used to spin a turbine which spins a generator.

• How much electrical energy generated in the USA is produced by fossil and nuclear fuel?

• Almost 90%of the electricity generated in the USA is produced by fossil and nuclear fuel.

Key Questions 4

Power Plants• To analyze the energy transformations in a

power plant, you can diagram the energy changes using arrows.

• A coal-burning power plant generates electrical energy through the following series of energy transformations.

Generating Electrical Energy• As the hot water boils, the steam rushes

through a turbine, which contains a set of narrowly spaced fan blades.

Generating Electrical Energy• The steam pushes on the blades and turns the

turbine, which in turn rotates a shaft in the generator to produce the electrical energy.

Power Plants

• Almost 90 percent of the electrical energy generated in the United States is produced by nuclear and fossil fuel power plants.

1. Describe the conversions between potential and kinetic energy that occur when you shoot a basketball at a basket.

2. Explain whether your body gains or looses thermal energy if your body temperature is 37o C and the temperature around you is 25o C.

3. Describe a process that converts chemical energy to thermal energy.

4. A light bulb converts 10 percent of the electrical energy it uses into radiant energy. Make a hypothesis about the other form of energy produced.

Questions Section 17.2