Given:
The height of the cliff, h=19.6 m
The initial velocity of the stone, u=0 m/s
The time period, t₀=0.5 s
To find:
a) The speed of the stone after 0.5 s
b) The speed of the stone when it hits the ground.
c) The time it takes for the stone to hit the ground.
Step-by-step explanation:
a)
From the equation of motion,

Where g is the acceleration due to gravity and v₀ is the velocity of th stone after 0.5 s
On substituting the known values,

b)
From the equation of motion,

Where v is the velocity of the stone when it hits the ground.
On substituting the known values,

c)
From the equation of motion,

Where t is the time it takes for the stone to reach the ground.
On substituting the known values,

Final answer:
a) The speed of the stone after 0.5 s is 4.9 m/s
b) The speed of the stone when it hits the ground is 19.6 m/s
c) The time it takes for the stone to reach the ground is 2 s