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.