Part A and B Cour × . Secure l https://session.masteringphysics.com/myd/masterin

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Part A and B

Cour × . Secure l https://session.masteringphysics.com/myd/mastering#/assign MasteringPhysics: Chapter 10 Assignment-Google Chrome Secure https://session.masteringphysics.com/myct/itemView? Chapter 10 Assignment Exercise 10.47 Study Mod Exercise 10.47 Part A A thin, uniform, metal bar, 2 m long and weighing 70 N, is hanging vertically from the ceiling by a frictionless pivot. Suddenly it is struck 1.4 m below the ceiling by a small 4-kg ball, initially traveling horizontally at 13 m/s. The ball rebounds in the opposite direction with a speed of 7 m/s Fir aterials Part B _001.pdf Type here to search

Explanation / Answer

a)given

L = 2m
W = 70 N

M = W/g = 70/9.8   = 7.14 kg

m = 4 kg

v1 = 13m/s

v2 = -7 m/s

apply conservation of momentum

m*v1*r = m*v2*r + I*w (here I is moment of inertia of rod)

put values

4*13*1.4 = 4*(-7)*1.4 + (M*L^2/3)*w

==> w = (4*13*1.4 + 4*(7)*1.4)/(M*L^2/3)

= (4*13*1.4 + 4*(7)*1.5)/(7.14*2^2/3)

= 11.76 rad/s

b)There are no unbalanced torques about the pivot, so angular momentum is a conserved. But the pivot exerts an unbalanced horizontal external force on the system, so the linear momentum is not a conserved

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