Didnt Newton allude to force as the cause of motion in Space,did Einstein also determined that?

Answer 1

Newton didn't "allude" to force as the cause of motion. He made it very clear that force is the only cause of motion. His laws of motion state that a body at rest stays at rest until a force is applied, and a body in motion stays in motion until a force is applied to change its motion. He also said that acceleration is the result of force and is proportional to the mass of an object.

Einstein didn't disagree with Newton's laws of motion. What he did was show that space and time and mass are not constant everywhere from all viewpoints, as Newton believed, and therefore the measurement of motion is more complicated than Newton thought.

Answer 2

Actually, no. What Newt's law says is that it takes a net force on a body to CHANGE its velocity. The body may already be in motion, but a net force is needed to change that motion. A change in motion (more properly called a change in velocity) is known as acceleration.

Mass has inertia, which can be indicated by something called momentum (p = mv); where v is that "motion" you are talking about and m is the mass of the thing in motion. We can write dp/dt = d(mv)/dt = mdv/dt = ma = f; where dp/dt is a change in momentum over time and dv/dt is a change in velocity (motion) over time. dv/dt = a acceleration as mentioned earlier.

So there we have it f = ma, another of Newt's laws. So we can write f/m = a which means a net force acting on a mass m will give that mass an acceleration a. That is, a net force causes a change in motion, but not the motion (v) itself.

Einstein's theories recognize f/m = a, but they did not derive that relationship. What Einstein did was show that mass, more properly rest mass, increased as the velocity of a body increased. Thus, in dp/dt = d(mv)/dt we get dm/dt v + mdv/dt instead of just mdv/dt like Newt got. So to change momentum (dp/dt) we need extra force to account for the change of mass as well as the change in velocity.

Answer 3

Newton's laws did not differentiate between the earth and space in his laws.