WAEC - Physics (1997 - No. 2)
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\(ms^{-2}\)
17.3\(ms^{-2}\)
20\(ms^{-2}\)
24.5\(ms^{-2}\)
125\(ms^{-2}\)
200\(ms^{-2}\)
คำอธิบาย
\(v^2 = u^2 +2aS = 0 +2\times(25-5)\)
\(v^2 =0+ 20\times 20 = 400\);
v =\(\sqrt{400}= 20(ms^{-2}\)