What types of change in motion causes acceleration?

Answer 1

Motion is the change of position over time.

The rate of change of position is called or speed.

Speed combined with its direction is called velocity.

The rate of change of velocity is called acceleration.

So, motion in which the speed or direction are changing is accelerated motion.

The question uses the word cause, which may be confusing. Technically when a

force is applied to a mass, there is acceleration. When there is acceleration the

velocity changes. If the object was in motion to begin with, it would speed up or

slow down or change direction. If the object was at rest, the force would have

caused an increase in speed from zero, so it would start moving. Therefore if you

think of a causal relationship, it would be more proper to say force causes

acceleration, which IS a change in motion.

For an example, an easy one is your bicycle. If you pedal, you are applying force.

That force cause the bicycle's speed to increase ... acceleration ... and you are in

motion. If you apply more force, you will go faster. If you apply the brakes, you will

slow down which is also acceleration (because speed is changing).

There is only one way to have motion without acceleration and that is to travel

at a constant velocity ... constant speed in a straight line. In practice, there is

no motion without acceleration for any period of time, because there is always

some minute change in speed or direction.

Answer 2

Motion occurs when unbalanced forces are involved. You have acceleration when this motion speeds up, slows down or changes direction.