The acceleration of a body must be zero at a point where--?

Question

1) The instantaneous velocity is zero but changing
2) The instantaneous velocity is not zero but changing
3) The instantaneous velocity is constant
4) The average velocity is zero

Answer 1

A mass (body) has acceleration/deceleration any time the velocity changes over time. That's the definition of acceleration; in math talk a = del v/del t, where del v means change in velocity and del t means change in time (i.e., an interval of time).

1) del v <> 0 (velocity is changing here) so a = del v/del t <> 0
2) del v <> 0 again; so a <> 0
3) del v = 0 (velocity is NOT changing, it's constant); so a = del v/del t = 0/det t = 0
4) ave v = del v/2 = 0; so that del v = 0 and a = del v/del t = 0

1, 2, and 3 are straightforward. Some answerers have said 4 is correct sometimes. I think it's correct all the time because as del v --> 0 the average v -->0 and a -->0 because of the a = del v/del t relationship.

ANS: 3 and 4.

Answer 2

number 3, and sometimes 4 here's why:
1) if velocity is changing, then an object is accelerating regardless of instantaneous speed
2) if velocity is changing, then an object is accelerating regardless of instantaneous speed
3) velocity remains constant, therefore acceleration remains constant
4) if the velocity remains zero, then it is not accelerating, but if it going in circles, or back and forth, it's changing acceleration

Answer 3

actually. Throw a ball vertically upwards. At optimal top its velocity is 0 even though it has the acceleration by way of gravity performing on it. This reasons it to fall back to earth. evaluate a swinging pendululum. on the factor of optimal swing its velocity is 0 even though it has an acceleration back in the direction of the mid-factor.

Answer 4

3 & 4 are the same and htey are answer