4. A diver of mass, m drops from the board 10.0 m above the water's surface. Suppose the diver vaults off the springboard, leaving it with an initial speed of 3.50 m/s upward. Use energy conservation to find his speed when he strikes the water. 10.0 m 5.00 m KE₁ = 0 PE₁ = mgyi 2 KEJ = mv² PE= = 0

24. A skier of mass 70 kg is pulled up a slope by a motor-driven cable. How many horsepower output must a motor have to pull him 100 m up a 30° frictionless slope at a constant speed of 2 m/s? a.700 b. 0.94 c. 746 d. 1.06 a b d

4. A 2.5 kg object falls vertically downward in a viscous medium at a constant speed of 2.5m/s. How much work is done by the force the viscous medium exerts on the object as it falls 80.0cm? A. -2.0 x 10 J B. -39 J C. 39 J D. 2.0 × 10 J E. O J

1. A 23.0 kg child is playing on a swing with a length of 2.5 m. If the swing starts from rest and makes an angle of 40.0◦ with the vertical at the top of the swing, a) determine the child’s speed at the bottom of the swing neglecting friction. b) If the swing has a speed of 2.8 m/s at the bottom, determine the work done by friction during the downswing and, bonus) assuming the force of friction is constant, determine the maximum angle the swing attains on the upswing after passing through the bottom. Hint: Use the approximation that cos θ ≈ 1 − 1 2 θ 2 for angles given in radians.

DETAILS SERPSE10 7.8.P.035.MI. (a) the work done by this force on the particle 1 A single conservative force acts on a 5.30-kg particle within a system due to its interaction with the rest of the system. The equation F, 2x + 4 describes the force, where F, is in newtons and is n meters. As the particle moves along the x axis from x 1.02 m tox-6.20 m, calculate the following (b) the change in the potential energy of the system (c) the kinetic energy the particle has at x 6.20 m if its speed is 3.00 m/s at x 1.02 m 3 Need Help? MY NOTES Pa ASK YOUR TEACHER PRACTICE ANOTHER