K.E. = 1/2 m v2
e.g. this dog has a mass of 7 kg and is running at 6 m/s
its kinetic energy is 0.5 x 7 x 36 = 126J
Calculating Energy
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The kinetic energy of an object depends on its mass
and its speed K.E. = 1/2 m v2 e.g. this dog has a mass of 7 kg and is running at 6 m/s its kinetic energy is 0.5 x 7 x 36 = 126J |
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The gravitational potential energy of an object on Earth
depends on its mass and its height. (we usually assume an object has zero g.p.e. at the Earth's surface) G.P.E. = m g h e.g. this man is 5m above the water. His mass is 75 kg. His g.p.e. is 75 x 9.8 x 5 = 367.5J |
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The elastic potential energy stored in a spring depends on
its extension and its stiffness E.P.E. = 1/2 k x2 e.g. the spring in this toy gun has a stiffness of 700N/m. It is squashed 5cm before shooting a ball. It stores 0.5 x 700 x (0.05)2 = 0.875J of energy |
