posted by Miriam .
A man (mass = 78.6 kg) is jogging through the woods and runs straight into a large oak tree at 6.1 m/s. Rebound speed is measured at 5.2 m/s in the opposite direction. If the time of contact with the tree is 0.041s, what is the magnitude of the force that the tree exerts on the man?
F•Δt = Δ(m•v) = m• Δv= m(v2-v1),
F = m(v2-v1)/Δt = 78.6(6.1 – (-5.2))/0.041= 21663 N