Question

9. An object falls 10 m from rest before entering some water. Assuming negligible air
resistance, what is the time taken to reach the water?
A)
1.02 ms
B)
1.02 s
C
1.43 ms
D)
1.43 s​

Answer 1

In the given question ,

the initial velocity of the object (v₀) = 0 m/s

The acceleration due to gravity (g) = 9.8 m/s²

The distance traveled by the object ( s) = 10 m

there is negligible air resistance,

Applying the second equation of motion,

s= v₀t + 1/2 gt²,

the body is initally at rest

t =$\sqrt{2s/g$

substituting the value;

10 = 0*t + 1/2 (9.8 * t²)

t =$\sqrt{2*10/9.8$

t = 1.43 seconds

Hence the answer is D) 1.43 s.