Hi Brian,

You firstly need to figure out the total angular momentum before they come to rest. That is done by adding the momentum of each seperate particle. The turn table have angular momentum L = Iw = 80 * 0,2 = 16,

while the runner have angular momentum L = Iw = 55*3^2*-0,8 = -396

(the angular velocity of the runner is calculated using v = wr, with tangential velocity 2,4 and radius 3, and remember to add the minus-sign, since the runner is running in the opossite direction).

When they come to rest, they are treated like a single object with a common moment of inertia of 575 (as you allready calculated). Then you just apply the law of conservation of angular momentum

L_1 = L_2

L_table + L_runner = L_rest

16-396 = 575 * w

w = (16-396) / 575

w = -0,68695

The minus-sign just shows that the table is now turning in the runners direction.

You firstly need to figure out the total angular momentum before they come to rest. That is done by adding the momentum of each seperate particle. The turn table have angular momentum L = Iw = 80 * 0,2 = 16,

while the runner have angular momentum L = Iw = 55*3^2*-0,8 = -396

(the angular velocity of the runner is calculated using v = wr, with tangential velocity 2,4 and radius 3, and remember to add the minus-sign, since the runner is running in the opossite direction).

When they come to rest, they are treated like a single object with a common moment of inertia of 575 (as you allready calculated). Then you just apply the law of conservation of angular momentum

L_1 = L_2

L_table + L_runner = L_rest

16-396 = 575 * w

w = (16-396) / 575

w = -0,68695

The minus-sign just shows that the table is now turning in the runners direction.