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how do i find the answer to this?
A student of mass 55kg dives from rest off a 10.5 m tower into water:
determine
if the student comes to rest 2.6m under the water. determine the average force that the water exerts on the diver?
i need help im stuck
Can anyone help me with this ?mechanical euation
1 Answer
- ?Lv 76 years ago
The work done by the water equals average force (F) times distance (s). This work changes the kinetic energy from its initial value (just above the water) to zero (at the deepest point below the water).
So
( KE_final) - (KE_initial) = Work done on student by water
0 - 1/2 m v^2 = - F s (minus sign because the force the water exerts is opposite to the displacement)
F s = 1/2 m v^2
F = (1/2 m v^2) / s
Now note that the kinetic energy just before entering the water equals the gravitational potential energy the student had relative to thewater level when he was on the tower:
1/2 m v^2 = m g h.
So
F = m g h / s
= 55kg * 9.8 N/kg * 10.5m / (2.6m)
(= 2177 N)
= 2.2 * 10^3 N
