An object falls freely from a height of 25m onto the roof a building 5m high. Calculate the velocity with which the object strikes the roof (g=10\(ms^{-2}\)
A
17.3\(ms^{-2}\)
B
20\(ms^{-2}\)
C
24.5\(ms^{-2}\)
D
125\(ms^{-2}\)
E
200\(ms^{-2}\)
Verified Correct Answer: B.
Physical Principles & Numerical Solution
\(v^2 = u^2 +2aS = 0 +2\times(25-5)\)
\(v^2 =0+ 20\times 20 = 400\);
v =\(\sqrt{400}= 20(ms^{-2}\)
Source: Myschool Past Questions Archive (Record #26289)