University Physics (OpenStax) Vol 1, 2021 P2311 Homework 5 (Ch. 5) Assigned: Problems Ch. 5 P 29, 30, 31, 39, 40, 41, 42, 43, 46, 52, 53, 67 Ch 5 Problems 29. Rocket sled. F_net = ma = 4.12x10^5 N 30. a) a = 11.1 m/s^2 b) a_4 = 45.4 m/s^2 31. a = -253 m/s^2 i or +253 m/s^2 "opposite to the motion of the rocket sled". 39. a = 1.6 i -0.8 j m/s^2 40. a = 5.6 i + 0 j m/s^2 41. a) W_on_earth = 1467 N ~ 1500 N b) m = 150 kg on Earth or Moon 42. a) a = (30000-10000*1.62)/10000 = 1.38 m/s^2 FIX b) No because Fg = 98,000 N > F_thrusters 43. a) Fh/Fw = 5.00 times b) |Fnet| = 3750 N angle = 11.3 deg from horizontal w = 19.6 N 46. F_engine = 7230 N FIX Steps to solve: 1) Find m_car = W/g 2) Find a = Delta v / Delta t 3) Find F_net = ma 4) Find F_engine = Fnet + f_friction F_eng = 5880 + 1350 = 7230 N 52. a) friction = 692 N opposite the direction of acceleration b) F_feet = 932 N opposite the direction of acceleration 53. Given W_H = 14 N and W_P = 18 N. F on History book = Fg + F_PH = W_H + F_PH = 0 F_PH = 14 N down "PH"=Physics on History By Newton's 3rd: F_HP = 14 N up F on Physics book = Fg + F_DP + F_HP "HP"=History on Physics = W_P down + F_DP up + W_H down = 0 So F_DP = W_P + W_H = 14 + 18 = 32 N In summary: F_PH = 14 j N F_EP = -18 j "EP" = Earth on Physics book F_HP = -14 j F_DP = 32 j Desk on Physics book 67. a) a = g sin 30 = 4.9 m/s^2 b) F_2 = mg sin 30 = 9.8 Check #40 and #67.