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Forces can change the shape of objects. Forces acting on an object can change their shape as well as make them accelerate. Forces can stretch or squash objects.
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Forces acting on an object can change their shape as well as make them accelerate. • Forces can stretch or squash objects. • A lot of the time forces that change the shape of an object are destructive. Think of car accidents or someone breaking a chair leg. These forces have all squashed or stretched material to breaking point. • However, forces changing the shape of an object can also be put to good use. • Can you think of some applications where forces squashing or stretching an object is useful?
When a spring is squashed or stretched by a force, energy is transformed into elastic potential energy and stored within the spring. (We can say that work has been done on the spring.) • When the force is removed, this energy is converted into other forms which return the spring to its original length. • The same thing happens when you pull back an elastic band. This process of storing elastic potential energy is useful for spring toys, wind-up clocks and vehicle suspension systems.
Can you think of objects that use this ability to store elastic potential energy? Toys store energy in coiled up springs Old wind-up clocks store energy in coiled up springs Shock absorbers on cars store energy when the car hits a bump and then return the spring to its original length, smoothing out the ride for the passengers.