In the winter activity of tubing, riders slide down snow covered slopes while si
ID: 1289482 • Letter: I
Question
In the winter activity of tubing, riders slide down snow covered slopes while sitting on large inflated rubber tubes. To get to the top of the slope, a rider and his tube, with a total mass of 73 kg, are pulled at a constant speed by a tow rope that maintains a constant tension of 350 N.
How much thermal energy Is created in the slope and the tube during the ascent of a 30-m high 120-m long slope?
I really am stuck on this one, I don't even know where to start. An answer with the steps will be greatly appreciated. Thanks so much!!
Explanation / Answer
The change in internal energy is only gravitional PE because the tube is being drug up at a constant speed. Since it is at a constant speed, the change in KE is 0.
Change in PE = m*g*h = 73 kg * 9.8 m/s^2 * 30 m = 21462 J
Work done on the system is from the force
Work = force * distance = 350 N * 120 m = 42000 J
So, work added 42000 J to the system, but the rider's energy only increased 21462 J. Therefore, friction took up the difference. Friction is where the thermal energy comes from
Q = 42000 J - 21462 J = 20538 J.