A) 2100\[m/{{\sec }^{2}}\]downwards
B) 2100\[m/{{\sec }^{2}}\]upwards
C) 1400\[m/{{\sec }^{2}}\]
D) 700\[m/{{\sec }^{2}}\]
Correct Answer: B
Solution :
Velocity at the time of striking the floor, \[u=\sqrt{2g{{h}_{1}}}=\sqrt{2\times 9.8\times 10}=14m/s\] Velocity with which it rebounds. \[v=\sqrt{2g{{h}_{2}}}=\sqrt{2\times 9.8\times 2.5}=7\ m/s\] \[\therefore \] Change in velocity \[\Delta v=7-(-14)=21m/s\] \[\therefore \] Acceleration \[=\frac{\Delta v}{\Delta t}=\frac{21}{0.01}=2100\ m/{{s}^{2}}\] (upwards)
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