Q. Four marbles are dropped from the top of a tower one after the other with an interval of one second. The first one reaches the ground 4 seconds. When the first one reaches the ground the distances between the first and second, the second and third and the third and forth will be respectively
A) 35,25 and 15 $m$
B) 30,20 and 10 $m$
C) 20,10 and 5 $m$
D) 40,30 and 20$\ m$
Explanation
(a) For first marble, $h_{1} = \frac{1}{2}g \times 16 = 8g$
For second marble, $h_{2} = \frac{1}{2}g \times 9 = 4.5g$
For third marble, $h_{3} = \frac{1}{2}g \times 4 = 2g$
For fourth marble, $h_{4} = \frac{1}{2}g \times 1 = 0.5g$
$\therefore h_{1} - h_{2} = 8g - 4.5g = 3.5g = 35m.$
$h_{2} - h_{3} = 4.5g - 2g = 2.5g = 25m$ and
$h_{3} - h_{4} = 2g - 0.5g = 1.5g = 15m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.