Question

16. Balls are thrown vertically upward in such a way that the next ball is thrown when the previous one
is at the maximum height. If the maximum height is 5 m, the number of balls thrown per minute wil
be
(a) 40
(c) 60
(b) 50
(d) 120
ance​

Answer 1

Explanation:

total time you have = 60 sec

we are going to apply second equation of motion,

$s = ut + \frac{1}{2} \times a {t}^{2}$

we know that time going to go up is equal to come down and we are not given intial velocity, so to avoid too much calculation, we observe the motion from the path from which ball comes down in order to find the time taken by each ball to go up.

so put u=0 and proceed

s= 5

a=10

now formula becomes,

$s = \frac{1}{2} a {t}^{2}$

now putting values

5= 1×10 t²/2

t² = 1

t = 1

so each ball takes 1 sec. to reach its top height.

so no. of balls thrown per minute = 1× 60

= 60 balls