A 71.2-kg boy is surfing and catches a wave which gives him an initial speed of 1.60 m/s. He then drops through a height of 1.62 m, and ends with a speed of 8.51 m/s. How much nonconservative work (in kJ) was done on the boy? KJ Supporting Materials Physical Constants An object with a mass of 50.0 kg is fired with an initial speed of 1.22 x 102 m/s at an angle of 30.0 above the horizontal from a 156 m high cliff (take ground level to be y = 0 m). (a) Determine the initial total mechanical energy (in ]) of the system of the projectile and the earth. J (b) If when the projectile is at its maximum height of y = 311 m, it is traveling 86.5 m/s, determine the amount of work (in J) that has been done on the projectile by air resistance. J (c) What is the speed (in m/s) of the projectile immediately before it hits the ground, if air resistance does one and a half times as much work on the projectile when it is going down as it did when it was going up? m/s Supporting Materials Physical Constants Points] DETAILS OSCOLPHYS1 7.P.011.WA. MY NOTES The center fielder for the school's baseball team throws a 0.150-kg baseball towards home plate at a speed of 32.0 m/s and an initial angle of 40.0. What is the kinetic energy of the baseball at the highest point of its trajectory? J Supporting Materials Physical Constants