Question

A metal ball of mass 5 kg falls from a height of 490 m. How much
time it will take to reach the ground ? (g = 9.8 m/s2)
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Answer 1

We know that, according to the Newton's law,

h = ut+1/2 g t^2.

Where,

h is  height or distance of the object under motion = 490m .

g is acceleration of the body = 9.8m/s^2.

t is time.

u is initial velocity = 0

Hence,

490 = 0+ 1/2*9.8*t^2

490/(1/2*9.8) = t^2

t^2 = 490/(4.9)  

t^2 = 100

t = 10 seconds.

Answer: Ball takes 10 seconds to reach the ground