Answer:
2 m/s^2
Explanation:
from the question
v=15 m/s
t=7.5
a=?
from the first equation of motion
v=u+at
where,
v=final velocity
u=initial velocity
a=acceleration
t=time
from the question (u) will be zero because the body started at rest
v=u+at
15=(0)+a×7.5
15=7.5a
a=15/7.5
a=2 m/s^2
Answer:

Explanation:
Equation of the rocket is,

Here, v' is the relative velocity of rocket.
In space F is zero.
So,

Now the momentum can be obtained by multiply by m on both sides.

Now for maxima, 

Now,

Therefore, the mass of the rocket while having maximum momentum is 
S(travel distance)=85 ft
v (velocity)=15 ft/s
-----------------------------------
t (time)=?
Calculate the time with the formula for the velocity:
v=S/t
t=S/v
t=85 ft/(15 ft/s)
t=5.666s
1200 times 2.5 is 3000. So it flew 3000 kilometers.
Field strength =force/unit mass
= 14.8N/ 4kg = 3.7N/kg