A helicopter, starting from rest, accelerates straight up from the roof of a hospital. The lifting force does work in raising the helicopter. An 740-kg helicopter rises from rest to a speed of 9.5 m/s in a time of 4.0 s. During this time it climbs to a height of 7.4 m. What is the average power generated by the lifting force?

Spiderman, whose mass is 78.0 kg, is dangling on the free end of a 12.4-m-long rope, the other end of which is fixed to a tree limb above. By repeatedly bending at the waist, he is able to get the rope in motion, eventually getting it to swing enough that he can reach a ledge when the rope makes a 0 = 59.4° angle with the vertical. How much work was done by the gravitational force on Spiderman in this maneuver? kJ

A roller coaster of mass 80.0 kg is moving with a speed of 12.0 m/s at position A as shown in the figure. The vertical height above ground level at position A is 10.0 m. Neglect friction. 10 m 7 m - Potential Energy 0 What is the total mechanical energy of the roller coaster at point A? 5760 J 2080 J 37000 J 7840 J Page 18 of 30 13600 J

PHYS 111 W24: Tutorial Quiz #6 Problem 1: A skier of mass 70 kg if pulled up a slope by a motor-driven cable. (a) How much work is required to pull him 60 m up a 30 degree slope (frictionless) at a constant speed of 2 m/s? (b) What power must a motor have to perform this task? Problem 2: Three ice skaters meet at the center of a rink and each stands at rest facing the center, within arm's reach of the other two. On a signal, each skater pushes themselves away from the other two across the frictionless ice. After the push, Skater A with mass 80 kg moves in the negative y-direction at 3.5 m/s and skater B with mass 75 kg moves in the negative x-direction at 4 m/s. Find the x- and y-components of the 90 kg Skater C's velocity after the push. Assume a birds-eye view of the situation for your coordinates.