Thread: Would Like to Know? on velocity

What is it that are the only things that can cause velocity?Is it as such that we do only say certain things can cause velocity like force and energy? Are these what would be the only things that cause or initiate movement or velocity?

Velocity doesn't need a cause. A body in constant motion or at rest will remain in motion or at rest until a force acts on it. See Newton's laws of motion.

But to produce a change in velocity a force must be applied. Refer again to Newton's laws of motion. Smart man Newton.

Newton's 2nd Law of Motion is important in this case, which roughly states:

"the rate of change of momentum of an object is directly proportional to the resultant (or net) force acting upon it"

Or written mathematically,



in the case of a constant mass system



and so



thus



where F is the resultant force (N), m is the mass of an object (kg) and a is the acceleration (ms^-2).

Therefore

and

combining these gives



where k is a constant with a value of 1 provided that the units are Newtons, kilograms and metres per second per second.

Newton's 2nd Law of Motion does have a caveat, however, as it does not apply to objects with speeds approaching that of the speed of light- as is shown by Einstein's Theory of Special Relativity, the mass of an object increases with extreme speeds.