question_answer

A particle is projected vertically upward. The value of g is\[10\text{ }m/se{{c}^{2}}\]. If 10 and 16 seconds be the times at which it is at the same height while ascending and descending respectively. Then velocity of projection is

A)  260 m/sec        

B)  160 m/sec

C)  130 m/sec       

D)  110 m/sec

Correct Answer: C

Solution :

: Time for reaching highest point \[=\frac{16-10}{2}+10=13\,\sec \] \[\therefore \] \[v=u-gt\] \[0=u-gt\] Or \[u=gt\] \[=10\times 13\] \[=130\text{ }m/s.\]