Question

A parent pulls a sled and rider with a combined weight of 50 kg up a 20-meter high hill and then gives the sled a push, providing an initial velocity of 4 m/s. Frictional forces acting on the sled do 2000 joules of negative work as the sled moves down the hill. Find the total energy of this system.

a) 100,000 J
b) 96,000 J
c) 92,000 J
d) 88,000 J

Answer 1

The question seeks the total energy of a sled system on a hill, which includes its potential energy, kinetic energy, and work done by friction. The calculation reveals that the total energy is 8200 J, contradicting the provided options.

Step-by-step explanation:

The question is about calculating the total energy of a sled system as it moves downhill. To do this, we need to consider both the potential and kinetic energy of the system, as well as the work done by friction. The potential energy (PE) can be found using the formula PE = mgh, where m is the mass, g is the acceleration due to gravity (9.8 m/s2), and h is the height. In this case, PE = 50 kg × 9.8 m/s2 × 20 m = 9800 J. The initial kinetic energy (KE) can be calculated using KE = 0.5 × m × v2, giving us KE = 0.5 × 50 kg × (4 m/s)2 = 400 J. The frictional forces do -2000 J of work (negative because it is work against the motion). The total energy of the system is thus the sum of the potential, kinetic, and work done by friction: 9800 J + 400 J - 2000 J = 8200 J, which corresponds to none of the options given (a-d).