Answer : Its acceleration is, 
The velocity after 5 s is, 31.25 m/s
The distance traveled by the time it reaches 50 m/s is, 200 m
Solution :
First we have to calculate the acceleration.
Formula used : 
where,
a = acceleration
v = change in velocity = 50 - 0 = 50 m/s
t = time = 8 s
Now put all he given values in the above formula, we get

Therefore, its acceleration is, 
Now we have to calculate the velocity after 5 second.
Formula used : 
where,
v = final velocity
u = initial velocity = 0 m/s
a = acceleration = 
t = time = 5 s
Now put all the given values in the above formula, we get

Therefore, the velocity after 5 s is, 31.25 m/s
Now we have to calculate the distance traveled by the time it reaches 50 m/s.
Formula used : 
where,
s = distance traveled
Now put all the given values in the above formula, we get


Therefore, the distance traveled by the time it reaches 50 m/s is, 200 m