Energy Transfer and Loss

The law of conservation of energy states that energy cannot be created or destroyed only transferred. Based on the diagram, energy is transferred from coal (6000 Units) to the turbine (4500 units) and then onto the generator (4005 Units) ; then to the power polls (3950 Units). How much energy is “lost” from coal to turbine ?

• 4,500 units

• 1,450 units

• 150 units

• 1,500 units

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Jack was practicing with his pinewood derby car. Pinewood derby cars are placed at the top of a large hill, on a track and released. The car then rolls down the hill, the fastest one wins the race. He really wanted to win this year. He wanted to increase the energy transfer from gravity to his car. He felt that the time it took to travel to the bottom was too slow. What way can he increase the transfer?

• He can decrease the weight of the car.

• He can make the front end more blocky.

• He can increase the weight of the car as long as it meets the requirements.

• He can add more wheels.

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If energy is lost to the environment when transferring energy, which choice below would NOT help to increase efficiency?

• Increase the use of nuclear power or other alternative power sources

• Increase the insulation in the existing structures

• Increase the use of energy efficient light bulbs and appliances

• Increase the power entering the system

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There is some energy “loss” at the light bulb. The light bulb is an incandescent bulb. Incandescent bulbs work by having gas in a chamber and then heating a filament, or piece of wire. The hot filament turns red, gets hot, and reacts with the gas in the bulb to create light. What is the best way to decrease the energy “loss” in the light bulb?

• Use a different type of bulb, like a LED.

• Use a light bulb that uses less voltage.

• Use a light bulb that emits less light.

• Use a colored light bulb.

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When a car travels, the motor transfers chemical energy into mechanical energy and then rotates the wheels, which make contact and exchange energy by friction with the road. This contact from the wheels is great during dry weather. During rain and snow, the transfer from the wheels by friction to the road is not as good. What is one solution to this problem?

• Don’t drive in the rain or snow.

• Have the tire completely smooth, increasing the area of contact, thus increasing the friction.

• Put deep grooves in the tires so the water and snow will go into the grooves allowing the rest of the tire to make better contact with the road.

• Change the height of the car by adjusting the shock absorbers.

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Heat loss to the environment occurs when matter is hotter than its surroundings. Numerous solutions have been created to solve this problem. Below is an example of one possible solution. Double walled cups are a solution to the problem because:

• They act as insulators and retain the heat of the matter inside.

• They act as conductors and move the heat through the system.

• They help increase heat transfer to the surrounding environment.

• They help reduce heat loss due to radiation to the surrounding environment.

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The Bonneville Salt Flats in Nevada are known as the place to go to set land speed records, in fact they have races there every year in September. The reasons that the salt flats are such a great place to set land speed records is due to the dry, hard packed and salty land. Even though the terrain remains the same, each year teams must modify their vehicles to set new records. One solution that teams can use to increase energy transfer and increase their speed is:

• Use larger tires on the vehicle to increase contact with the salt flats.

• Build more efficient engines to burn fuel cleaner to provide more power.

• Add mass to their vehicle to increase the force and acceleration.

• Create a flat front vehicle to provide more down force and friction.

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Home energy efficiency is a growing industry. There are multiple ways that homes can be made more energy efficient. Using the figure below and your knowledge of science; one solution to creating more efficient home is:

• Use efficient windows and doors to decrease heat transfer.

• Use efficient appliances to transfer more energy within the home.

• Reduce insulation to increase the energy transfer at the roof.

• Reduce power entering the home to increase overall efficiency.

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When a car travels, the motor transfers chemical energy into mechanical energy and then rotates the wheels, which make contact and exchange energy by friction with the road and create movement. There is a significant amount of energy loss within the system. Using the information below, one way to decrease energy loss within a gasoline vehicle system is:

• Reduce the exhaust heat.

• Idle the vehicle more often.

• Use the water pump less often.

• Increase the friction within the engine.

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A lamp that plugs into a wall socket draws energy, which flows through a thin wire in the bulb, causing it to heat up until it glows. What energy transformations are taking place?

• Chemical → light → electrical

• Mechanical → sound → light

• Thermal → solar → electrical

• Electrical → thermal → light