Question

A stone thrown vertically upwards went up 98 m and came down. How long was it in the air?

Answer 1

Answer:

Final Velocity of stone,v=0 because after attaining the maximum height it will come at rest and begin to fall down.

Initial velocity,u=98m/s

Acceleration due to gravity,a= -9.8 m/s because the motion of ball is opposite to the direction of the acceleration caused due to gravity.

∴ Using first kinematical equation, we get

v = u + at

0=98+(-9.8)t

-98= -9.8t

∴ t = -98/-9.8

∴ t=10 seconds

By using second kinematical equation, we get

s = ut + 1/2 at^2

∴ s = 98*10 + 1/2 *(-9.8)*10*10

∴ s = 980 + 1/2 * (-980)

∴ s = 980 + (-490)

∴ s = 490 m

Hope it helps

Answer 2

Answer:

8.945 second

Explanation:

I don't know