<span>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 = 78 kg * 10 m/s^2 * 30 m = 23400 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 23400 J. Therefore, friction took up the difference. Friction is where the thermal energy comes from
Q = 42000 J - 23400 J = 18600 J.
Therfore, friction generated 18600 J of heat to the surroundings.</span>
Work = (force) x (distance)
80 J = (force) x (4 m)
Force = (80 J) / (4 m) = 20 N
That's IF the force was in the same direction as the 4m of motion.
If the force was kind of slanted, then it had to be stronger, and
it had a component of 20N in the direction of the motion.
The statements that correctly compare the gravitational force with the electrical force are the following:
-The gravitational force can be attractive.
-The electrical force can be repulsive.
-The electrical force can be attractive.
-Any two objects experience a gravitational force between them.
it cannot be reuse and replaced for long period of time.hope it helps u
