Question

a child drops a ball from a height of 10m full stop assume that its velocity increases uniformly at the rate of 10 M per second square find find the velocity with which the ball strikes the ground and find the time taken by wool to reach the ground

Answer 1

v square = usquare + 2 aH
0 = u square + 2 (10)(10).
-200 = u square
hence u = -10√2 m/s.
therefore u = 14.14 m/s
(negative sign represents velocity along -ve Y axis.)

also , v= u + at
0 = 10√2 + 10 × t. ( taking g= 10 m/ s square)
hence, 10√2 = 10t
hence. t= √2 =1.414 sec.

Answer 2

   ANSWER    

Acceleration(a) = 10 m/s²

Initial Velocity(u) = 0 m/s

Final velocity be 'v' m/s

g = 10 m/s²

Now Using equation of motion:

v² + u² = 2gh

v = √2gh

  = √200

  =  10√2 m s⁻¹

Now, Let the time be 't' sec.

.

Equation of motion:

h = ut + 1/2gt²

h = 1/2gt²

t = √(2h/g)

t = √2 sec

∴ Velocity = 10√2 m s⁻¹

∴ Time = √2 second