Q13 of 26 Page 16

A uniformly moving cricket ball is turned back by hitting it with a bat for a very short time interval. Show the variation of its acceleration with time. (Take acceleration in the backward direction as positive).


We shall be considering only the horizontal motion of the ball (no effect due to gravity). The ball is moving uniformly before hitting the bat, thus, it will have no/zero acceleration. When the bat hits the ball an impulsive force is generated which provides acceleration to the ball. The ball returns with the same speed thereafter.


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11

A ball is bouncing elastically with a speed 1 m/s between walls of a railway compartment of size 10 m in a direction perpendicular to walls. The train is moving at a constant velocity of 10 m/s parallel to the direction of motion of the ball. As seen from the ground,

 12

Refer to the graphs in Fig 3.1. Match the following.

Graph Characteristic


(a) (i) has v > 0 and a < 0 throughout.


(b) (ii) has x > 0 throughout and has a point with v = 0 and a point with a = 0.


(c) (iii) has a point with zero displacement for t > 0. (d) (iv) has v < 0 and a > 0.


 14

Give examples of a one-dimensional motion where

(a) the particle moving along positive x-direction comes to rest periodically and moves forward


(b) the particle moving along positive x-direction comes to rest periodically and moves backward.


 15

Give example of a motion where x > 0, v < 0, a > 0 at a particular instant.