GRADE 7
Name:
Kinetic Energy
Kinetic energy is “movement energy”. This means that when an object is moving, it is
doing so with kinetic energy. Sometimes you can see the movement of the object,
other times you can only see the effect of the object moving. For example, when you
drop an object, like a book, you can see the book moving toward the ground. In a
closed electric circuit, the charges are moving through the circuit. You cannot see the
charges moving, but you can see the effect of them doing so in that the light bulb
will light up.
Relationship between Potential and Kinetic Energy
Potential energy is stored energy in an object. As a result, the object has the
“potential” to do work. When you hold a ball in your hand, it has potential energy –
gravitational potential energy, because it has the potential to fall out of your hand
and to the ground as a result of gravity. When the ball is dropped, it moves toward
the ground. This means that the potential energy has been changed into kinetic
energy. When the ball is in your hand, it has lots of potential energy, but no kinetic
energy. As soon as it falls, it has lots of kinetic energy and no potential energy.
Lots of potential energy. No kinetic energy.
1
3
2
© e-classroom 2014 No potential energy.
Lots of kinetic energy.
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Grade 7 Term 3 Natural Science: Energy and Change: Potential and Kinetic Energy: Potential Kinetic Energy
Potential and kinetic energy
GRADE 7
Identify what type of energy (potential or kinetic) is present in each of these examples:
1) A skydiver waiting to jump out of the plane.
2) A car stopped at a red traffic light.
3) A child sliding down a slide.
4) A skydiver jumping out of the plane.
5) A child waiting at the top of a slide, ready to slide down.
6) A car moving through an intersection at a green light.
7) A bowling ball travelling toward the pins.
8) A person holding the bowling ball about to release it.
Helpful Skill: Drawing Energy Flow Diagrams
The change or transfer of energy from one form to another can be represented in a
flow diagram. Flow diagrams show an input, a process and an output.
An INPUT is what “goes in” to the system or process. A PROCESS is what changes
occur and how they occur. The OUTPUT is the result or what “comes out” of the
system or process.
If we use the above example of dropping a ball, we could draw an energy flow
diagram that looks like this:
INPUT
Ball is held up in
hand, above the
ground.
Ball has
gravitational
potential energy.
PROCESS
Ball is dropped out of
hand.
Ball is pulled to ground
by gravity.
Potential energy
changes into kinetic
energy.
OUTPUT
Ball falls to the
ground.
Ball has kinetic
energy.
Activity 2
Draw an energy flow diagram for the following scenarios.
1) A skydiver waits in a plane and then jumps out of the plane.
2) A child waits at the top of a slide and then slides down the slide.
3) A car is stopped at a traffic light and when it turns green, the car moves off and drives down the road.
© e-classroom 2014 www.e-classroom.co.za
Grade 7 Term 3 Natural Science: Energy and Change: Potential and Kinetic Energy: Potential Kinetic Energy
Activity 1
GRADE 7
Activity 1
Identify what type of energy (potential or kinetic) is present in each of these
examples:
1) A skydiver waiting to jump out of the plane. Potential Energy
2) A car stopped at a red traffic light. Potential Energy
3) A child sliding down a slide. Kinetic Energy
4) A skydiver jumping out of the plane. Kinetic Energy
5) A child waiting at the top of a slide, ready to slide down. Potential Energy
6) A car moving through an intersection at a green light. Kinetic Energy
7) A bowling ball travelling toward the pins. Kinetic Energy
8) A person holding the bowling ball about to release it. Potential Energy
Activity 2
Draw an energy flow diagram for the following scenarios.
1) A skydiver waits in a plane and then jumps out of the aeroplane.
INPUT
Skydiver waits
in plane, high
above ground.
Skydiver has
gravitational
potential energy.
PROCESS
OUTPUT
Skydiver jumps out
of plane.
Skydiver falls to the
ground.
Skydiver is pulled to
ground by gravity.
Skydiver has kinetic
energy.
Potential energy
changes into
kinetic energy.
© e-classroom 2014 www.e-classroom.co.za
Grade 7 Term 3 Natural Science: Energy and Change: Potential and Kinetic Energy: Potential Kinetic Energy
Answer sheet
GRADE 7
2) A child waits at the top of a slide and then slides down the slide.
INPUT
Child waits at the
top of the slide,
above ground.
Child has
gravitational
potential energy.
PROCESS
OUTPUT
Child pushes off the
edge of the slide.
Child slides
down towards
ground.
Child pulled to the
ground by gravity.
Child has kinetic
energy.
Potential energy
changes into
kinetic energy.
3) A car is stopped at a traffic light and when it turns green, the car moves off and drives down the road.
INPUT
Car is stopped
(at rest) at red
traffic light.
Car has potential
energy.
PROCESS
INPUT
Red light turns green
and car is able to
move forward.
Car moves
forward and
drives down the
road.
Potential energy
changes into kinetic
energy.
© e-classroom 2014 Car has kinetic
energy.
www.e-classroom.co.za
Grade 7 Term 3 Natural Science: Energy and Change: Potential and Kinetic Energy: Potential Kinetic Energy
Answer sheet