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ANSWERS TO SAQS
Subject: Physics
Unit: Principles of Physics
Topic: 1-2 Principles of Physics
Level: 3
© DistanceLearningCentre.com, 2022 1
, Subject: Physics
Unit: Principles of Physics
Topic: Principles of Physics
Level: 3
ANSWERS TO SAQs
SAQ 1:
1. List as many different types of energy as you can. Try to think of an
example of each type of energy that you come up with.
2.
a) A 20 N crate is lifted 5 m from the floor onto a shelf at a speed of
Topic 1 15ms-1. How much kinetic energy is used to lift the crate? Assume
that the force of gravity is 10ms-2
b) How much potential energy does the 20 N crate have whilst sat
on the self?
3.
a) A 30N force is used to pull a block along a friction-free surface
for 10m. How much work has been done?
b) A travel kettle has a power of 1kW. It boils a cup of water in 80
seconds. How much energy is transferred?
c) A person whose mass is 80kg runs up two flights of stairs,
totalling 20m high, in 10 seconds. What is the average power of
the person?
4. Draw a Sankey diagram to represent a filament lamp where only
10% of the electrical energy is converted into light energy.
Answers:
1.
• Gravitational Potential – satellite in orbit
• Kinetic – a ball rolling down a hill
• Elastic Potential - stretched hair bobble
• Sound – car horn
• Thermal/Heat – toaster
• Electric – between 2 charged particles
• Magnetic – Earth
• Chemical – food
• Light – lightbulb
• Nuclear – Nuclear power plant
You may find other types as well
© DistanceLearningCentre.com, 2022 2
, Subject: Physics
Unit: Principles of Physics
Topic: Principles of Physics
Level: 3
ANSWERS TO SAQs
2.
a)
To calculate KE determine mass first
Mass (kg) = weight (N) ÷ Acceleration of gravity (ms-2)
Mass = 20 N ÷ 10 ms-2
Mass = 2 Kg
𝟏
KE (J) = 𝟐 mass (Kg) x Velocity (ms)2
KE = 1 Kg x (15 ms-1)2
KE = 1 Kg x 225 ms-1
KE = 225 J
b)
PE (J) = mass (Kg) x gravity (ms-2) x height (m)
PE = 2 Kg x 10 (ms-2) x 5 (m)
PE = 100 J
3.
a) Work done = Force x distance moved
W = 30 x 10
W = 300J
b) Power = Work done (energy transferred) / time
W=Pxt
W = 1000 x 80
W = 80,000J
c) Power = Work done (energy transferred) / time
Assuming all work done is transferred into the Gravitational potential
energy (GPE) of the person:
Energy transferred = final GPE (mgh)
Power = mass x gravitational field strength x height / time
Power = (80 x 10 x 20) / 10
© DistanceLearningCentre.com, 2022 3
ANSWERS TO SAQS
Subject: Physics
Unit: Principles of Physics
Topic: 1-2 Principles of Physics
Level: 3
© DistanceLearningCentre.com, 2022 1
, Subject: Physics
Unit: Principles of Physics
Topic: Principles of Physics
Level: 3
ANSWERS TO SAQs
SAQ 1:
1. List as many different types of energy as you can. Try to think of an
example of each type of energy that you come up with.
2.
a) A 20 N crate is lifted 5 m from the floor onto a shelf at a speed of
Topic 1 15ms-1. How much kinetic energy is used to lift the crate? Assume
that the force of gravity is 10ms-2
b) How much potential energy does the 20 N crate have whilst sat
on the self?
3.
a) A 30N force is used to pull a block along a friction-free surface
for 10m. How much work has been done?
b) A travel kettle has a power of 1kW. It boils a cup of water in 80
seconds. How much energy is transferred?
c) A person whose mass is 80kg runs up two flights of stairs,
totalling 20m high, in 10 seconds. What is the average power of
the person?
4. Draw a Sankey diagram to represent a filament lamp where only
10% of the electrical energy is converted into light energy.
Answers:
1.
• Gravitational Potential – satellite in orbit
• Kinetic – a ball rolling down a hill
• Elastic Potential - stretched hair bobble
• Sound – car horn
• Thermal/Heat – toaster
• Electric – between 2 charged particles
• Magnetic – Earth
• Chemical – food
• Light – lightbulb
• Nuclear – Nuclear power plant
You may find other types as well
© DistanceLearningCentre.com, 2022 2
, Subject: Physics
Unit: Principles of Physics
Topic: Principles of Physics
Level: 3
ANSWERS TO SAQs
2.
a)
To calculate KE determine mass first
Mass (kg) = weight (N) ÷ Acceleration of gravity (ms-2)
Mass = 20 N ÷ 10 ms-2
Mass = 2 Kg
𝟏
KE (J) = 𝟐 mass (Kg) x Velocity (ms)2
KE = 1 Kg x (15 ms-1)2
KE = 1 Kg x 225 ms-1
KE = 225 J
b)
PE (J) = mass (Kg) x gravity (ms-2) x height (m)
PE = 2 Kg x 10 (ms-2) x 5 (m)
PE = 100 J
3.
a) Work done = Force x distance moved
W = 30 x 10
W = 300J
b) Power = Work done (energy transferred) / time
W=Pxt
W = 1000 x 80
W = 80,000J
c) Power = Work done (energy transferred) / time
Assuming all work done is transferred into the Gravitational potential
energy (GPE) of the person:
Energy transferred = final GPE (mgh)
Power = mass x gravitational field strength x height / time
Power = (80 x 10 x 20) / 10
© DistanceLearningCentre.com, 2022 3
