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WorksheetsEnergy Work Power Thermal
Total questions: 23
Worksheet time: 38mins
Which energy transfer takes place when a wood log burns in a fire?
Chemical to thermal energy
Chemical to kinetic energy
Electrical to heat energy
Nuclear to heat energy
A
B
C
D
2.5 m/s
10 m/s
25 m/s
125 m/s
A trolley is pushed with a force that causes it to move a certain distance. It moves in the direction it is pushed.
Which represents the combination of force and distance that means the smallest amount of work is done on the trolley?
Force = 20N
Distance = 20N
Force = 40N
Distance = 10N
Force = 50N
Distance = 6.0N
Force = 70N
Distance = 4.0N
1/2 mv^2
mgh + 1/2 mv^2
mgh - 1/2 mv^2
mgh
8.0/0.5 x 100%
7.5/0.5 x 100%
0.5/8.0 x 100%
7.5/8.0 x 100%
A
B
C
D
Lifting the box from the ground to the high shelf slowly
Lifting the box from the ground to the high shelf quickly
Lifting the box from the ground to the low shelf slowly
Lifting the box from the ground to the low shelf quickly
Thermal -> kinetic and gravitational potential
Gravitational -> kinetic + thermal
Kinetic -> Gravitational potential + thermal
Gravitational potential + kinetic
-> thermal
x
y
z
x + z
When a battery powered LED torch is switched on, which is the useful energy change within the LED?
Electrical to thermal
Chemical energy to light energy
Chemical energy to electrical energy
Electrical energy to light energy
A
B
C
D
An object from a height of 5.0 m.
Air resistance can be ignored.
As it hits the ground the object has 750 J of kinetic energy.
What is its mass?
15 kg
50 kg
75 kg
150 kg
Which device is designed to convert chemical energy into kinetic energy?
An a.c. generator
A battery-powered torch
a car engine
a fan
A machine is very efficient. What does this mean?
It produces a large amount of power
It uses very little energy
It wastes very little energy
It works very quickly
A crane on a building site lifts bricks of total mass 200 kg, initially at rest on the ground, with uniform acceleration.
When the bricks are 5.0 m from the ground, they have a speed of 5.0 m/s.
How much work is done during this process?
2.5 kJ
10 kJ
12.5 kJ
35 kJ
It has a maximum value at X
It has a maximum value at Y
It has a maximum value at Z
It has the same value at W, X, Y and Z
An object has a mass of 500 kg. It moves with a speed of 30 m/s.
What is its kinetic energy?
7.5 kJ
15 kJ
225 kJ
450 kJ
A lamp has a power input of 5.0 W. It wastes 1.0 W of power heating the surrounding.
What is the efficiency of the lamp?
20 %
50 %
80 %
120 %
A boy produces an average power output of 60 W as he rides his bicycle for 2.0 minutes. How much useful energy does he expend?
0.50 J
30 J
20 J
7200 J
A box of mass 8.0 kg is lifted from the ground and placed on a shelf. The box gains 100 J of potential energy.
The box falls off the shelf. Air resistance can be ignored.
At what speed does the box hit the ground?
3.5 m/s
5.0 m/s
25 m/s
28 m/s
A car is moving along a straight road. The car has 1.6 MJ of kinetic energy. The car accelerates for 20 s until the kinetic energy of the car increases to 2.5 MJ.
What is the minimum average power developed by the car engine?
45 W
205 W
45 kW
205 kW
0.44 m/s
1.0 m/s
1.4 m/s
2.0 m/s
