Module 25

Module 25- Conservation of Energy Saturday, October 14, 2023 12:07 PM 1. A man on a motorcycle plans to make a jump as shown in the figure. If he leaves the ramp with a speed of 30.5 m/s and has a speed of 28.7 m/s at the top of his trajectory, determine his maximum height (h) (in m) above the end of the ramp. Ignore friction and air resistance. 2. As shown in the figure below, a skateboarder starts at point A on the ramp and rises to point B, a maximum height of h = 2.15 m above the top of the ramp. T If the amount of work done against friction is insignificant, determine his initial speed (in m/s) at point A. 3. The specialty of an athlete on the women's track team is the pole vault. She has a mass of 54 kg and her approach speed is 9.4 m/s. When she is directly above the bar, her speed is 1.2 m/s. Neglecting air resistance and any energy absorbed by the pole, determine the amount(in m) she has raised herself as she crosses the bar. 4. A 65.8-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 1.63 m, and ends with a speed of 8.51 m/s. How much nonconservative work (in kJ) was done on the boy? 5. An object with a mass of 40.0 kg is fired with an initial speed of 1.38 X 102 m/s at an angle of 30.0 above the horizontal from a 164 m high cliff (take ground level to be y = 0 m). a. Determine the initial total mechanical energy (in J) of the system of the projectile and the earth. b. If when the projectile is at its maximum height of y = 362 m, it is traveling 97.8 m/s, determine the amount of work (in J) that has been done on the projectile by air resistance. 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