# Kinetic Energy

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• Created by: LSmith
• Created on: 26-03-14 14:54
Work done and energy transferred are measured in...
joules, J.
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Objects gain ____________ when they are raised.
gravitational energy
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Moving objects have ........
kinetic energy.
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Work is done whenever a _____ moves something.
force
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Whenever work is done, _____ is transferred from one place to another.
energy
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W = F × d W = ?
W = work done (joules, J)
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W = F × d F = ?
F = force applied (newtons, N)
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W = F × d D = ?
D = distance moved in the direction of the force (metres)
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e.g. 10 N is applied to move the box 2 m.
Work done = 10 × 2 = 20 J
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Power is a measure of how ____ work is being done, so how quickly ______ is being transferred.
quickly, energy
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P = E ÷ t P = ?
P = power (watts, W)
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P = E ÷ t E = ?
E = work done (joules, J)
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P = E ÷ t t = ?
t = time taken (seconds, s)
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e.g. An electric drill transfers 3000 J in 15 s. What is its power?
Power = 3000 ÷ 15 = 200 W
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On Earth we always have the force of _____ acting on us.
gravity
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When we are above the Earth’s surface we have potential (stored) energy. This is called........
gravitational potential energy
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What does the amount of gravitational potential energy an object on Earth has depends on?
its mass, and its height above the ground.
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If an object is lifted, work is done ______ gravitational force.
against
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Ep = m × g × h Ep = ?
Ep = the change in gravitational potential energy (joules)
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Ep = m × g × h m = ?
m = mass (kilograms, kg)
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Ep = m × g × h g = ?
g = gravitational field strength (newtons per kilogram, N/kg)
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Ep = m × g × h h = ?
h = change in height (metres, m)
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e.g. A book with a mass of 0.25 kg is lifted 2 m onto a bookshelf. If g is 10 N/kg, what is the change in gravitational potential energy?
Ep = 0.25 × 10 × 2 = 5 J
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All ______ objects have kinetic energy.
moving
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What does kinetic energy an object has depends on?
its mass, and its speed.
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Ek = ½ × m × v2 Ek = ?
Ek = kinetic energy (joules, J)
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Ek = ½ × m × v2 m = ?
m = mass (kilograms, k)
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Ek = ½ × m × v2 v = ?
v = speed (metres per second, m/s)
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e.g. What is the kinetic energy of a 1000 kg car travelling at 5 m/s?
Ek = ½ × 1000 × 52 = 500 × 25 = 12500 J
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What is a pendulum?
A simple machine for transferring gravitational potential energy to kinetic energy, and back again.
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When the bob is at the highest point of its swing, it has no ________ _______, but its gravitational potential energy is at a maximum.
kinetic energy
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As the bob swings downwards, gravitational potential energy is ________ to kinetic energy, and the bob accelerates.
transferred
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At the _____ of its swing, the bob’s kinetic energy is at a maximum and its gravitational potential energy is at a minimum.
bottom
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As the bob swings upwards, its kinetic energy is transferred to ___________ ________ _____ again
gravitational potential energy
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At the top of its swing, it once again has no ______ ______, but its gravitational potential energy is at a maximum.
kinetic energy
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The bob’s swing will become lower with each swing, because some energy is also transferred as ___ to the surroundings.
heat
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## Other cards in this set

### Card 2

#### Front

Objects gain ____________ when they are raised.

#### Back

gravitational energy

### Card 3

#### Front

Moving objects have ........

### Card 4

#### Front

Work is done whenever a _____ moves something.

### Card 5

#### Front

Whenever work is done, _____ is transferred from one place to another.