Two pendulums of equal length l = 0.45 m are suspended from the same point.The pendulum bobs are steel spheres.The first bob is drawn back to make a 35° angle with the vertical.If the first bob has mass 0.25 kg and the second has mass 0.85 kg,how high will the second bob rise above its initial position when struck elastically by the first bob after it is released?
A)1.7 cm
B)1.4 cm
C)2.0 cm
D)2.3 cm

Question

Quizplus · Accepted Answer

In an elastic collision, both momentum and kinetic energy are conserved. The initial potential energy of the first bob is converted to kinetic energy at the bottom of the swing. Using conservation of energy and momentum, the velocity of the second bob can be calculated. The height it rises can then be found using conservation of energy. The correct height is approximately 1.7 cm.

Two Pendulums of Equal Length L = 0