Answer:
The answer is 0.83 seconds.
Explanation:
The formula of free fall is following:

Where g=9.8 m/s^2 and t=2 seconds, the rock takes:

19.6 meters. This is the half distance of the cliff. The whole distance is 39.2 meters. So it takes:

2.83 second to fall down completely. The rock takes the second half of the cliff in 0.83 seconds
the acceleration or the next force acting on the body is constant
Hello,
<u>Solution for A:</u>
Force = 3.00N
Mass = 0.50 Kgs
Time = 1.50 Seconds
According to newton's second law of motion;
Force = Mass times Acceleration(a)
3.00 = 0.50 * a
a = 3.00/0.50 = 6.00 m/s^2
We know that acceleration = Velocity / time
So Velocity = time * acceleration = 1.50 * 6 = 9.00 m/s^2
<u>Solution for B:</u>
The net force = 4.00N - 3.00N = 1.00N to the left
Force = 1.00N
Mass = 0.50Kg
Time = 3.00 Seconds
Again; F = MA (Where F is force, M is mass and A is acceleration)
1.00N = 0.5 * A
A = 1/0.5 = 2 m/s^2
Velocity = Acceleration * Time = 2 * 3 = 6 m/s