Question

a ball thrown vertically upwards returns to ground after 8 seconds. calculate the initial velocity of the ball and the maximum height reached by the ball (g=10m/s^2

Answer 1

Hope it help u...............

Answer 2

Concept:

If the other features of a body's motion are understood, a set of equations known as kinematics can be used to determine the unknown aspect. The two kinematical equations to be utilized here are- v = u + gt and v² = u² + 2aS.

Given:

The time taken by the ball to return to the ground = 8 secs

acceleration due to gravity, g  = 10 m/s²

Find:

We need to determine the initial velocity, u of the ball and the maximum height reached by the ball, S.

Solution:

The ball is thrown up and returns in 8 seconds;

We know, that the accent time equals the descent time.

Accent time = descent time

Therefore, the time required to ascend thus equals 8/2=4 seconds

Now, consider the ball's initial velocity

Since, s = 0, g being 10m/s² and t = 4secs

Therefore, the first kinematic equation becomes, v = u + gt

Since the ball was thrown upwards, acceleration is negative,

Therefore, v = u - gt

0 = u - 10×4

u = 40 m/s

Now, consider the ball's motion from its highest point to the ground when calculating height.

Using, v² = u² + 2gS, we get

S = (v²- u²)/2g

S = 0 – (40)²/(- 2× 10)

S = 1600/20

S = 80m

Thus, the initial velocity of the ball is 40 m/s and the maximum height reached by the ball is 80m.

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