Why do forces make an object move?

[scilearner]

Hello everyone,

 

May be the question is when something has energy and there is no resistance why does it move? Thanks

[Physicsfan]

consider a stationary object such that the vector sum of all forces acting on it is zero, or in other words there is no force on the body at all.

This body has no potential energy.

Now if a force F (A push) is applied on the body for a time t seconds, then the velocity obtained by the body would be obtained from the equation [imath]v=at[/imath].

Now the energy gained by the body(Kinetic energy) is the same as the work done by the force on the body, because energy is transferred to the body.

(law of conservation of energy).

Now we know that work is [imath]F S[/imath]

now we know [imath]F=ma[/imath], but we do not know the magnitude of the displacement.This can be obtained from the equation [imath]v^2=u^2+2aS[/imath] or [imath]v^2=2aS[/imath].

"play" with the equation and you get [imath]S = v^2 /2a[/imath]

now multiply [imath]ma[/imath] to the expression and you get [imath]K = 1/2mv^2 [/imath] which as you know is the formula for kinetic energy.

[scilearner]

Thanks Physics fan I always like when equations start to make sense My question is however more on let's say I push a box on the floor, it gains energy and moves. Why does an object decide to change in position when energy is gained. Is this something we know because of observation. I think this question is more philosophical.

[swansont]

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