question_answer

A ball falls from a height of 20m on the floor and rebounds to a height of 5m. Time of contact is 0.02 seFind the acceleration during impact?

A) \[12m/{{s}^{2}}\]                   

B) \[1000m/{{s}^{2}}\]

C) \[2000m/{{s}^{2}}\]                

D) \[1500m/{{s}^{2}}\]

Correct Answer: D

Solution :

[d] \[v-u=at\] \[-10-20=0.02\times a\] \[a=(-)\,1500\,m/{{s}^{2}}(retardation)5m\] \[u=2\times 10\times 20v=\sqrt{2\times 10\times 5}\]             \[\downarrow u=20m/sv=-10m/s\uparrow \]