Pretty sure that it is 0.
PE = mgh
where
m = mass
g = acceleration due to gravity
h = height
Explanation:
potential energy= mgh
30 × 10 × 30 = 9000J or 9KJ
Answer:
m = 2218.67 kg
Explanation:
It is given that,
Initial velocity, u = 7.5 m/s
Final speed of an object, v = 0 (at rest)
Force, F = 5.2 kN
Time, t = 3.2 s
We need to find the mass of the object. Force acting on an object is given by :
F = ma
m is mass, a is acceleration

So, the mass of the object is 2218.67 kg