A 4-kg hammer is lifted to a height of 10 m and dropped from rest. What was the velocity (in m/s) of the hammer when it was at a height of 4 m from the earth? O12 O5 O11 O109.5

v = 10.84 m/s

Explanation:

using the equation of motion:

v^2 = (v0) ^2 + 2*a (r - r0)

due to the hammer starting from rest, vo = 0 m/s and a = g, g is the gravitational acceleration.

v^2 = 2*g (r - r0)

v = / sqrt{2 * (-9.8) * (4 - 10) }

= 10.84 m/s

therefore, the velocity at r = 4 meters is 10.84 m/s