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GCSE PHYSICS
ENERGY
ANSWERS AND MARK SCHEMES
QUESTIONSHEET 1
(a) work done = force  distance moved
50  10  2.5
= 1250 J/Joules
1
1
1
(b) (i)
Mike 1750
Jeff
1500
1
1
Jeff
1
(ii)
(iii) Mike
1
(c) force = work done
distance moved
1
1750 / 2 = 875N
875 / 10
87.5 kg
1
1
1
(Marks will be awarded for the calculation even if the work done by Mike was wrongly calculated in b(i))
TOTAL / 11
QUESTIONSHEET 2
(a) work done = force  distance moved
650  500
= 325 KJ/ 325,000 J
1
1
1
(b) 500  500 = 25 000 J
250 000 / 2000
= 125 W/watts
1
1
1
(c) 650  500 = 325 000 J
325 000 / 5000
= 65 W/watts
125 – 65 = 60 W/watts
1
1
1
1
Note: Do not deduct further marks if incorrect answer from b) is used correctly in subsequent calculations.
TOTAL / 10
GCSE PHYSICS
ENERGY
ANSWERS AND MARK SCHEMES
QUESTIONSHEET 3
(a) (i)
converted to/becomes/changes to kinetic energy.
(ii) 1 x 45
= 45 kJ/45,000 J
(b) velocity =
kinetic energy
0.5  mass
1000 / 10 = 100 kg
4500
0.5  10
= 30 ms-1
v=
(c) work done = gain in potential energy
= 45 kJ/45,000 J
1
1
1
1
1
1
1
1
1
TOTAL / 9
QUESTIONSHEET 4
(a) 120 10
= 1200 J/1.2 kJ
1
1
(b) 120 5
= 600 J
1
1
600  100
1200
= 50%
1
(ii) friction in wheels
1
(iii) oil wheels
1
(c) (i)
1
TOTAL / 8
GCSE PHYSICS
ENERGY
ANSWERS AND MARK SCHEMES
QUESTIONSHEET 5
(a) energy efficient bulb: 20 / 21  100
= 95%
1
1
standard bulb: 100 / 180  100
= 20%
1
1
fluorescent strip: 20 / 28  100
= 60%
1
1
(b) (i)
standard bulb
(ii) lost as heat
(c) use less electricity for the same light output
last longer so less resources used in a given time
1
1
1
1
TOTAL / 10
QUESTIONSHEET 6
(a) KE = ½ m v2
= ½  5000  32
= 22500 J
1
1
1
(b) 3 / 5
= 0.6 m/s
1
1
(c) ½  25 000  0.62
= 4500 J
1
1
(d) (i)
1
22 500 - 4 500 = 18 000 J
(ii) converted to heat
and sound
1
1
TOTAL / 10
GCSE PHYSICS
ENERGY
ANSWERS AND MARK SCHEMES
QUESTIONSHEET 7
(a) Watts
1
(b) one Watt = one Joule per second
1
(c) energy = force distance
= 80  10  30
= 24 000 J
1
1
1
(d) Power = energy / time
= 24 000 / 15
= 1600 W or 1.6 kW
1
1
1
TOTAL / 8
QUESTIONSHEET 8
(a) 55  10 = 550 N
(b) (i)
energy = force  distance
= 3.5  550
= 1925 J
(ii) 1925 J
1
1
1
1
1
(c) v2 = u2 + 2as
0 = 122 + 2  -10 x s
s = 144 / 20
= 7.2 m
1
1
1
1
(d) 900 / 3
= 300 W
1
1
TOTAL / 11
QUESTIONSHEET 9
(a) (i)
30  10  3
= 900 J/joules
1
1
(b) 900 J/joules
1
(c) (1) muscles of the man/food man has eaten/
chemical energy in food
1
(2) lift motor
1
TOTAL / 5
GCSE PHYSICS
ENERGY
ANSWERS AND MARK SCHEMES
QUESTIONSHEET 10
(a) (i)
600 kJ/600,000 J
(ii) 3.6 MJ/3,600 kJ
1
1
(b) energy of light bulb = 1 500 000 W
time = energy transferred / power
4 h 10 min/250 min
1
1
1
(c) (i)
1
electrical to heat energy
(ii) electrical to heat and light energy
1
(iii) electrical to heat and movement/kinetic energy
1
TOTAL / 8
QUESTIONSHEET 11
(a) (i)
potential energy to kinetic energy
1
(ii) kinetic energy to sound and kinetic energy
1
(iii) kinetic energy to potential energy
1
(b) (i) 300 / 1000  10
= 0.3  1.8
= 0.54 J
(ii) potential energy has become kinetic energy at the instant
it hits the ground
0.54
=
0.5  0.3
= 6 ms-1
1
1
1
1
1
1
TOTAL / 9
GCSE PHYSICS
ENERGY
ANSWERS AND MARK SCHEMES
QUESTIONSHEET 12
(a) using work done = force distance moved
430 4/4 = 430 W (Lucy)
450 4/6 = 300 W (Carol)
1
1
1
(b) Lucy
1
(c) her muscles
1
(d) Carol
She would do the most work as she was the heaviest/ had greatest weight
1
1
TOTAL / 7
QUESTIONSHEET 13
(a) supplied as part of nature/generated in a way that the Earth’s resources not used up.
1
(b) (i)
1
200
(ii) Wind does not blow all the time.
(c) (i)
rearranging equation
5  3300  60
= 990,000 M J
(ii) 495,000 MJ
1
1
1
1
1
TOTAL / 7
QUESTIONSHEET 14
(a) Joule
(b) (i)
energy = force  distance
0.3  10  0.5
1.5 J
1
1
1
1
(ii) 1.5 J
1
(iii) 0.3  10
3N
1
1
TOTAL / 7
GCSE PHYSICS
ENERGY
ANSWERS AND MARK SCHEMES
QUESTIONSHEET 15
(a) (i)
No loss of kinetic energy
(ii) lose energy as heat
and sound
1
1
1
(b) (Two from)
air bag - absorbs kinetic energy of driver
crumple zone – absorbs KE of car
seat belt – exerts force to stop driver
4
KE = ½ m v2
= ½  2000  152
= 225 000 J or 225 kJ
1
1
1
(ii) Force = energy / distance
= 225 000 / 30
= 7500 N
1
1
1
(c) (i)
TOTAL / 13
QUESTIONSHEET 16
(a) (i)
chemical
 electrical
 kinetic
1
1
1
(ii) work done = force x distance
= 3  1 = 3J
1
1
(iii) Power = energy / time
= 3 / 10 = 0.3 W
1
1
(b) (i)
potential
 kinetic
 electrical
 heat & light
(ii) KE = ½ m v2
= ½  1  22
(c) chemical
 heat
 kinetic
1
1
1
2
1
1
1
1
1
TOTAL / 17
GCSE PHYSICS
ENERGY
ANSWERS AND MARK SCHEMES
QUESTIONSHEET 17
(a) heat and light (either order)
2
(b) chemical
sound
1
1
(c) kinetic and sound (either order)
2
(d) heat and light (either order)
2
TOTAL / 8
QUESTIONSHEET 18
(a) Six from
kinetic, potential, electrical, heat, light, sound,
chemical, nuclear
(b) (i)
6
Newton
metre
1
1
(ii) conservation
changed
created
destroyed
1
1
1
1
TOTAL / 12
GCSE PHYSICS
ENERGY
ANSWERS AND MARK SCHEMES
QUESTIONSHEET 19
(a) too much emphasis on nuclear energy
not enough spent on renewable sources
1
1
(b) secondary source of energy
made from the others
1
1
(c) gas
oil
1
1
TOTAL / 6
QUESTIONSHEET 20
(a) (i)
the sun
1
(ii) photosynthesis
produces glucose / sugar which stores energy
1
1
(iii) plants die
subjected to high temperatures and pressures
over millions of years
1
1
1
(b) (i)
A
1
(ii) C
1
TOTAL / 8