question_answer

Water drops fall at regular intervals from a tap which is 5.0 m above the ground. The third drop is leaving the tap at the instant the first drop reaches the ground. How far above the ground is the second drop at that instant?

A) 1.25 m  

B) 2.50 m

C) 3.75 m         

D) 5.00 m

Correct Answer: C

Solution :

[c] : Let T be the time interval between the drops (1, 2, 3) falling from the tap as shown in the figure. Since distance covered by the first drop in time 2T is 5m,\[5=\frac{1}{2}g{{(2T)}^{2}}=2g{{T}^{2}}\]                 ...(i) Further, distance covered by the second drop in time T (from t = T to t = 2T), \[y=\frac{1}{2}g{{T}^{2}}\]   ...(ii) From eqns. (i) and (ii), y = 1.25 m Distance of the second drop from the ground \[=5-=5-1.25=3.75m\]