Cyberphysics - Questions on Energy Transfer

Questions on Energy Transfer

The following questions have their answers hidden under the blue rectangle - Mentally answer the question and then 'Mouse Over' the blue area to check whether you are correct!

Q1	The following devices change energy from one form to another: dynamo; microphone; loudspeaker; motor; lamp; voltaic cell
a	Which device changes electrical energy to light energy?
b	Which device changes sound energy to electrical energy?
c	Which device changes kinetic energy to electrical energy?
d	Which device changes electrical energy to kinetic energy?
e	Which device changes electrical energy to sound energy?
Q2	An electric motor wastes 15% of the energy supplied to it?
	What is its efficiency?
Q3	Are the following statements right or wrong?
a	The elastic energy of a compressed spring depends on how fast it is travelling
b	The gravitational potential energy of a ball increases as it rises up into the air?
c	The elastic energy of a spring depends upon the extent to which it has been stretched
d	If a child is travelling on a 'Big Wheel' at the fair. His/her gravitational potential energy is constant.
e	If a child is travelling on a 'Big Wheel' at the fair. His/her kinetic energy is constant as long as the speed that the wheel turns at is constant.
f	When a ball is thrown up into the air its kinetic energy is transformed into gravitational potential energy. When its height reaches a maximum its speed is zero.
g	When a current passes through a wire - the wire has kinetic energy because the electrons are moving.
h	If a car moves up a hill at a steady speed it is gaining both gravitational potential energy and kinetic energy
i	When a balls bounces on the floor some of its kinetic energy is changed into heat and sound. There is therefore less kinetic energy left to be converted into gravitational potential energy as it rises into the air again.
Q4	The diagram shows a fairground 'Big Wheel' with five chairs: A, B, C, D and E

	Which chair is gaining gravitational potential energy at the greatest rate?
Q5	The diagram shows a slide in a children's playground

a	A boy climbs the steps. What type of energy does he use?
b	What types of energy has the answer to part (a) been converted to by the time he reaches the top of the slide?

c	He slides down the slope. What form of energy corresponds to the fact that he is moving?
d	He stops before reaching the end of the slide. What final form has that energy been converted into
Q6	What energy changes take place in the following?
a	Bread being eaten
b	A dynamite stick exploding
c	A kettle of water placed on a gas ring
d	A lamp that is switched on
e	A skydiver jumping from a aeroplane
f	A mechanical toy driven by a battery
g	A sports whistle being blown
h	A turbine turning to charge up a battery
i	A windmill's sails turning to lift a sack of flour