Q38. Help me Please A man throws balls with the same speed vertically
upwards one after the other at an interval of
2 second. What should be the speed of the throw
so that more than two balls are in the sky at any
time? (Given g = 9.8 m/s2)
(1) More than 19.6 m/s
(2) At least 9.8 m/s
(3) Any speed less than 19.6 m/s
(4) Only with speed 19.6 m/s

The correct option is A.

We have t=2s

When the ball is thrown upward the final velocity become zero.

Therefore,

v=u+at

0=u−gt  

Here, g is acceleration due to gravity

u=gt

=9.8×2=19.6 m/s

Thus, when he throws a ball with a minimum speed of 19.6m/s in a time interval of 2s.

Then two balls can be in the air simultaneously.

a) electrical > light, sound, and thermal< < < <

) the mechanical energy of the firefighter moving.< < < < a) electrical > light, sound, and thermal< < < <

c) both a and b.

connect the batteries in series and hope