Examples Of Energy Being Converted (T4)

Question 1

List six ‘energy conversion devices’ that you can find anywhere..

Answer 1

• muscles
• electric motors
• light bulbs
• loudspeakers
• falling bodies
• car brakes

Question 2

Describe how a muscle converts energy…

Answer 2

• a muscle converts chemical energy into kinetic energy with some heat generated as a waste product
• the chemical energy is stored in the form of blood sugars and oxygen which react together to give movement
• there will also be some heat generated by the reaction and also by friction within the muscle

Question 3

How does an electric motor converts energy?

Answer 3

• it converts electrical energy into kinetic energy with heat and sound generated as waste products
• the motor gets its energy from an electrical supply
• the wasted heat comes from friction and electrical heating of the internal wiring
• the wasted sound is a product of the mechanics working and creating noise

Question 4

How does a light bulb convert energy?

Answer 4

• converts electrical energy into light, but all bulbs also produce some heat
• old fashioned filament bulbs produce a lot of heat and require a lot of energy but modern CFL’s and LED’s are a lot more energy efficient

Question 5

How does a loudspeaker convert energy?

Answer 5

• it converts electrical energy into sound with some heat wasted due to the heating of the internal wires

Question 6

How do falling bodies convert energy?

Answer 6

• a falling object converts the gravitational potential energy that it possesses due to its position into kinetic energy as it accelerates towards the ground
• if no air, then there would be no wasted by-product, but in normal circumstances friction will produce heat

Question 7

How do car brakes convert energy?

Answer 7

• the brakes convert the car’s kinetic energy into heat in order to slow down the car
• they get very hot in the process
• some modern hybrid cars convert the kinetic energy into electrical energy to use at a later stage. This involves charging the battery system then using the battery to help power the car.

Question 8

Explain the energy conversions involved in a cyclist consuming food then cycling off somewhere. His bike has a generator fitted to the wheel which activates a lamp when the bike is in motion..

Answer 8

• having eaten, the cyclist converts the chemical energy stored in his body into movement energy
• the movement is initially in the cyclists legs and is then transferred to the bike
• the cyclist is also producing additional heat energy which is lost to the surroundings
• friction in the bike will also result in energy being converted from movement into heat and sound
• the Dynamo or generator fitted to the bikes wheel converts some of the movement energy of the wheel into electrical energy
• the lamp then converts the electrical energy into light and heat
• as electric current flows in the Dynamo lamp circuit, heat will be produced in the conducting wires too