Question

identify positive negative and zero acceleration question is the motion of a body in a straight line with constant speed​

Answer 1

Answer:

When a particle moves with a constant speed in the same direction, neither the magnitude nor the direction of velocity changes and so acceleration is zero. ... If the initial velocity of a body is negative, then even in case of positive acceleration, the body speeds down.

Answer 2

Answer:

According to our principle, when an object is slowing down, the acceleration is in the opposite direction as the velocity. Thus, this object has a negative acceleration. In Example D, the object is moving in the negative direction (i.e., has a negative velocity) and is speeding up.

Mathematically, a negative acceleration means you will subtract from the current

value of the velocity, and a positive acceleration means you will add to the current value of the velocity.

When a particle moves with a constant speed in the same direction, neither the magnitude nor the direction of velocity changes and so acceleration is zero.