Question

find out the whether the acceleration is positive or negative in the given situation, A a ball rolling on a level groud b a train starting from the station c the motion of a stone thrown up-when it goes up and comes down ​

Answer 1

Answer:

.Retardation.

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Answer 2

(a) A ball rolling on a level ground: negative

(b) A train starting from the station: positive

(c) The motion of a stone thrown up when it goes up: negative, and when it comes down: positive

• When a ball rolls on a level ground, the rolling friction acting between the ball and the ground decelerates the ball and there is no external force present. That is why, the acceleration is negative.
• When a train starts from the station, it does so, with a slow speed and then picks up a high speed. This means that the velocity increases with time and hence, the acceleration is positive.
• When a stone is thrown up, the stone decelerated due to air friction and also because it is travelling in the opposite direction of gravity. So, the acceleration is negative.

• When the stone is coming back down, it velocity increases due to the acceleration due to gravity and hence, the acceleration is positive.