Question

please give ur final answer right now....please​

Answer 1

Answer:

12 sec

Explanation:

According to the given question,

Mass = m = 40 kg

g = 10m/s^2 (Say)

u = initial velocity = 72 m/s

F = Force and a = acceleration

v = final velocity = 0 (here)

t = time to go up

And we are asked to find the total time.

Let, total time = T

So, when the ball is moving up there are two forces which are acting on it in downward direction. As acceleration due to gravity is downwards.

Force on ball due to gravity,

• F = ma

• F = 40×10 = 400 N

And also the air is pushing down the ball when its going up.

Hence, the force 80N is in the downward as well as the force of 400N.

So, Fnet = 400+80 = 480 N (downward)

So, Now its acceleration

= 480/40

= 12 m/s^2 (downward)

Now Using, v=u-at

Here the acceleration is negative.

(Putting the values we get)

• 0 = 72 - 12×t

• t = 72/12

• t = 6 sec

So, T = 6×2 = 12 sec ans.