University Physics (OpenStax) Vol 1, 2021 P2311 Homework 9 (Ch. 9) Assigned: Problems Ch. 9 Concept Q's: 1, 3, 11,13 Problems: 18,21,25,26,29,30,31,32,37,41,42,43,53,54,63,69 Ch. 9 Concept Qs: 1. Since K=p^2/2m, then if the momentum is fixed, the object with the smaller mass has more kinetic energy. 3. Yes; impulse is the force applied multiplied by the time during which it is applied (J=F Delta t), so if a small force acts for a long time, it may result in a larger impulse than a large force acting for a small time. 11. No, he is not a closed system because a net nonzero external force acts on him in the form of the starting blocks pushing on his feet. 13. Yes, all the kinetic energy can be lost if the two masses come to rest due to the collision (i.e., they stick together). Ch 9 Problems 18. a) p_elephant = 1500 kg m/s (to right) b) |P_el/P_dart| = 625 c) P_hunter = 666 kg m/s (to right) 21. P_rain = 278,000 kg m/s 25. a) -1,500,000 N (to left) b) -100,000 N (to left) 26. Favg = 6.7x10^6 N 29. F = 2100 N 30. a) duration of impact = 2.86x10^03 sec b) average force = 1100 N (left) 31. p(t)= 10i + 20t j kg m/s F(t) = dp/dt = 0i + 20j N 32. a) (i) impulse for 04 problems with no work.