A) \[\text{21}00\text{m}/{{\text{s}}^{\text{2}}}\]
B) \[\text{14}00\text{ m}/{{\text{s}}^{\text{2}}}\]
C) \[\text{7}00\text{ m}/{{\text{s}}^{\text{2}}}\]
D) \[~\text{4}00\text{ m}/{{\text{s}}^{\text{2}}}\]
Correct Answer: A
Solution :
Let u be the velocity with which the ball hits the ground, then \[{{u}^{2}}=2gh\] \[=2\times 9.8\times 10=196\] \[\therefore \] \[u=14\,\,m/\sec \] If \[v\] be the velocity with which it rebounds, then \[{{v}^{2}}=2\times 9.8\times 2.5=49\] \[\Rightarrow \] \[v=7\,\,m/\sec \] \[\therefore \] \[\Delta v=(v-u)\] \[=7(m/\sec )-(-14m/\sec )\] \[=21\,\,m/\sec \] \[\therefore \] \[a=\frac{\Delta v}{\Delta t}=\frac{21}{0.01}=-2100\,\,m/{{s}^{2}}\](upward)
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