Question

A ball is thrown upwards with a speed of 100 M/s. show that the ball hits the ground with the same speed after returning from the highest point a gravity = 10 M/s2

Answer 1

Gravity reduces the vertical velocity by 10m/s every second, so in 10 seconds it will all be gone, and it will start down again. Making 20 seconds in flight.
(obviously ignoring air resistance and taking g as 10 rather than 9.81)

Answer 2

Answer:

The ball is thrown with a speed of 100m/s so if we apply newton laws of motion then we will get the value of maximum height as u^2 = 2gh.

100*100 = 2*10*h.

Thus, h = 500m.

Now, we got the maximum height of the flight as 500m. Again by applying the newton laws of motion we will get.

As, h = ut + 1/2gt^2.

500 = 100t - 5t^2.

t^2 - 20t + 100 =0.

(t-10)^2 = 0.

So, t=10sec.

Thus, the total time of the flight will be 2*10=20sec.