A person pulls a crate with 120 N of force against 100 N of friction a distance of 5 meters. Find the energy the person expends pulling the crate, the amount of energy converted to heat via friction, and the increase in the kinetic energy of the crate.
W=Fs=120•5 = 600 J
W(fr)=100•5=500 J
ΔKE=(120-100)•5=100J
To find the energy the person expends pulling the crate, you need to calculate the work done by the person. Work is calculated by multiplying the force applied by the distance traveled. In this case, the force applied by the person is 120 N and the distance traveled is 5 meters.
Work = Force × Distance
Work = 120 N × 5 m = 600 Joules
So, the energy the person expends pulling the crate is 600 Joules.
Next, to calculate the amount of energy converted to heat via friction, you need to find the work done against friction. Friction opposes the motion of the crate and the work done against friction is calculated by multiplying the force of friction by the distance traveled.
The force of friction is given as 100 N, and the distance traveled is 5 meters.
Work against friction = Force of friction × Distance
Work against friction = 100 N × 5 m = 500 Joules
Therefore, the amount of energy converted to heat via friction is 500 Joules.
Finally, to determine the increase in the kinetic energy of the crate, you can use the work-energy theorem. According to the work-energy theorem, the work done on an object is equal to the change in its kinetic energy.
Work done = Change in kinetic energy
Since the work done by the person is equal to the change in kinetic energy, we can use the work done value of 600 Joules obtained above.
Change in kinetic energy = 600 Joules
Hence, the increase in the kinetic energy of the crate is 600 Joules.