Physics I. Unit : potential energy and conservation of energy. A & B Please The

Question

Physics I. Unit : potential energy and conservation of energy. A & B Please

The figure shows a thin rod, of length L = 2.80 m and negligible mass, that can pivot about one end to rotate in a vertical circle. A heavy ball of mass m = 140 kg is attached to the other end. The rod is pulled aside to angle theta_0 = 17 degree and released with initial velocity V_0 = 0. (a) What is the speed of the ball at the lowest point? (b) Does the speed increase, decrease, or remain the same if the mass is increased?

Explanation / Answer

using energy conservation

KEi + Ui = KEf+Uf

KEi = 0 releasing from rest

Uf = 0 ( at lowest point h = 0)

mgh = mv^2/2

2gh = v^2

h = L-Lcostheta

v = sqrt(2gL(1-costheta))

given = L = 2.80 m

theta = 17 degree

v = 1.55m/s

part b )

speed remain same beacuse speed does not dpend on mass

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