Hi :)
Pressure is the force applied perpendicular to the surface of an object per unit area
The SI unit of pressure is N/m^2
Hope this helps!
Answer:
I think the answer is C. for 4. and then B. for 5.
I believe it'd accelerate at 1.25 m/s^2 instead of 1, as it lost 1/4 of its mass (.25), so now it is .25 of 1 faster.