Given parameters:
First velocity = 2.50m/s
Time of travel = 3s
Second velocity = 1.50m/s
Unknown:
The displacement during the first interval = ?
Velocity is the displacement of a body with time. Displacement is a distance move in a specific direction by a body.
Velocity = 
So;
Displacement = Velocity x Time taken
Now input the parameter for the first velocity and time of travel;
Displacement = 2.5 x 3 = 7.5m
The displacement id 7.5m
a = 7.8 m/s^2
Explanation:
Let Fnet = net force = ma
m = mass of the skydiver
a = acceleration caused by Fnet
W = weight = mg
f(air) = frictional force due to air resistance
Fnet = W - f(air)
= (100 kg)(9.8 m/s^2) - (200 N)
= 780 N
Therefore, the acceleration of the skydiver due to Fnet is
a = Fnet/m
= (780 N)/(100 kg)
= 7.8 m/s^2
Answer:
7.5secs
Explanation:
Using the equation of motion
v = u + at
v is the final velocity = 0m/s
u is the initial velocity = 9m/s
a is the deceleration = -1.2m/s²
t is the required time
Substitute;
0 = 9 + 1.2(t)
-9 = -1.2t
t = -9/-1.2
t = 7.5secs
hence it takes the child 7.5secs to stop