If a moving body has no acceleration does it mean that no force is acting on it?

Answer 1

It means there is no net force acting on it.

A plane in the air has no acceleration, but it does have forces acting on it.

Lift pushes it up

Gravity pushes it down

Air resistance opposes its movement

Thrust provides movement

When all these forces are equal the plane will move at a constant velocity. If one of these forces becomes greater the NET force on the plane will no longer be 0 and there will be an acceleration or deceleration.

Hope that helps.

Another example would be space as there are no opposing forces, if in space once a speed was that speed would be constant until you 1.) decelerated with a force in the opposite direction 2.) accelerated the speed past your current velocity in your current direction 3.) Get caught by some planets gravity and crash to you death (but then this question is the least of your problems)

Answer 2

NO, acceleration refers to change in speed, either speeding up(positive acceleration) or slowing down (negative acceleration.)

Zero acceleration merely means it is holding a constant speed, whatever that may be (including, but not limited to a constant speed of zero.)

Answer 3

No, an object with zero velocity does not necessarily have zero acceleration. The best example of this is an object that is thrown into the air. Let's look at that.

The object that is lofted up is constantly accelerated by gravity. The object will have some initial velocity, and its velocity will decrease under the influence (the constant acceleration) of gravity. At some point it will "stop" in air for an instant, and the velocity of the object will be zero. But gravity has always been accelerating the object, and it will continue to do so, pulling it back down to earth. The object was accelerating at g, which is the earth's gravitational constant, even during the instant that it was not moving.

Sooooo....in the above explanation, Quirkyquantummechanic appears to have successfully argued that "zero acceleration" is, in fact, a degree of acceleration, and is not the same as "no acceleration". Also, QQM indirectly pointed out that an object approaching zero velocity also approaches zero acceleration, and at the precise moment of zero velocity, the object is at zero acceleration albeit still under the influence of acceleration.

Therefore, the answer to the original question is still "Yes" - an object at zero velocity does have zero acceleration.

Answer 4

yes the acceleration is at zero because there is no change in acceleration if the velocity is constant

Answer 5

No, acceleration is a CHANGE in speed, something with 0 acceleration while not changing speed can still be moving.