Confused, how can an object have a=0 but still have a positive Force?

I'm somewhat confused trying to understand 鈭慒=M*A .





For example, If an elevator moves upward at at constant velocity V, then it has no acceleration (a=0) and the sum of all forces should equal to zero 0.


鈭慒 = F[Engine] - F[gravity] = 0.





But wouldn't that mean that the elevator is stationary and not moving !?!? If its moving upwards doesn't it need a Net positive Force? In that case how would acceleration still be 0? --ConfusedConfused, how can an object have a=0 but still have a positive Force?
Don't confuse velocity and acceleration. You can move without accelerating. You can't START moving or STOP moving without accelerating, but you can keep moving at a constant velocity with no force and no acceleration. Picture throwing a ball in outer space. It'll just keep on moving forever with no forces on it at all after you let go.





That's what's happening in the elevator. It accelerates up to a certain speed, then the engine exactly balances out gravity so it doesn't change that speed. During that period when the speed remains constant, there is no acceleration and no net force. But there is velocity.Confused, how can an object have a=0 but still have a positive Force?
';Constant velocity'; means no net force, no acceleration. As Newton's First Law says, in the absence of an external force, an object in motion will continue in motion in the same straight line.





It takes a nonzero force to go from v = 0 to a nonzero velocity. That's an acceleration. But it doesn't take any net force to maintain a constant velocity.





Newton was quite brilliant to realize this, given that in our world, things tend to stop unless you keep applying a force. But Newton's description of what is happening there is that there is a frictional force, and to maintain constant velocity you must apply a force to cancel out the friction and make the net force = 0.
because acceleration and Velocity are two separate thing, velocity riles on acceleration for changes, but no matter what the velocity it dose not affect the acceleration.





think of an object in space, it can stay moving forever with no net forces on it, ie. have a constant velocity but no acceleration.


same with your elevator with the equation of F1-F2=Ma, a=0


you end up with F1=F2 so there is a positive movement, but no acceleration (change in the ratio of Velocity)
Objects don't need a force to act on them in order to move. By Newton's first law, objects that have no net force acting on them either stay at rest or move with a constant velocity.