Various philosophers studied the basic ideas of cause of motion.

 

According to Aristotle,a constant external force should be applied continuously to an object in order to keep it moving with uniform velocity.

 

Later this idea was discarded and galileo gave another idea on the basis of the experiments on an inclined plane.

 

According to him,no force is required to keep an object moving with constant velocity.

 

It is the presence of frictional force that tends to stop moving objects.

 

After Galileo, it was Newton who made a systematic study of motion and extended the ideas of Galileo.