Page 133 - Knowledge Organiser Yr9 24-25

Knowledge Base: Science P1: Energy Year 9
5. Kinetic Energy
5.1
When will energy will be transferred to the kinetic store of an object?
When the object starts moving.
5.2
What is the equation to calculate the energy in the kinetic store?
Kinetic energy store = 0.5 x mass x velocity2
(Ek=1⁄2mv2)
6. Elastic Potential Energy
6.1
When will energy will be transferred to the elastic store of an object?
When it is stretched or compressed.
6.2
What is the equation to calculate the energy in the elastic store?
Elastic energy store = 0.5 x spring constant x extension2 (Ee=1⁄2Ke2)
6.3
What is spring constant?
How difficult it is to extend or compress an elastic object (the larger the spring constant, the more force required).
6.4
What is the unit for spring constant?
Newtons/metre (N/m).
5.3 What is the unit for mass? kilograms (kg)
5.4 What is the unit for velocity? metres per second (m/s)
Worked example questions:
A car is moving at a speed of 25m/s and has a mass of 990kg. Calculate the kinetic energy stored in the car as it moves.
A bird with a mass of 200g is flying at a speed of 5m/s. Calculate the kinetic energy stored in the bird as it flies.
Sam is riding his bike and has a kinetic store of 1440J.
The mass of Sam and his bike is 80kg. Calculate Sam’s speed.
6.5 What is the unit for extension? Metres (m).
6.6
How is the extension of a spring measured?
extension = extended length- original length
Worked example questions:
A trampoline spring has a spring constant of 150N/m. It is extended by 0.2m. Calculate the elastic store of energy in the spring.
A spring has a spring N/m. It is extended and stores 0.06J of energy. Calculate the extension of the spring.
constant of 12
elastic potential
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