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