Question

A merry-go-round (pictured) is sitting in a playground. It is free to rotate, but is currently stationary. You can model it as a uniform disk of mass 200 kg and radius 110 cm (consider the metal poles to have a negligible mass compared to the merry-go-round). The poles near the edge are 97 cm from the center.

Someone hits one of the poles with a 9 kg sledgehammer moving at 19 m/s in a direction tangent to the edge of the merry-go-round. The hammer is not moving after it hits the merry-go-round.

How much energy |ΔE| is lost in this collision? (enter a positive number for the absolute value in Joules)

Answer 1

You forgot to mention that this problem is part if your 8.01 MIT exam and asking for help during your exam is a violation of the Honor Code.

Answer 2

@ anonymous aha, you instead were casually around here...

Answer 3

so... no ideas for this problem???

Answer 4

m_1: The mass of the merry-go-round
m_2: The mass of the sledgehammer
v_1: The velocity of the merry-go-round before the collision
v_2: The velocity of the sledgehammer before the collision
v_1': The velocity of the merry-go-round after the collision
v_2': The velocity of the sledgehammer after the collision

v_1='(m_2*v_2)/m_1 (1)

you put your v_1 in eq (2) and ready


((0.5*m_1*v_1^2)+(0.5*m_2*v_2^2))-((0.5*m_1*v_1'^2)+(0.5*m_2*v_2'^2)) (2)

Answer 5

and the rotation?