Question

Assuming a mass of 0.04 g, what is the power exerted by the electrical forces on a fragment of fiber if the fragment has a velocity of 200 mm/s, 10 ms after ejection? For this problem, I used the formula P= Force * velocity = mass* (velocity/time)*velocity = (mass * velocity^2) /time. However I got the problem wrong. In the answer, they used the formula P= W/t = 1/2* (mass*velocity^2)/time. I am confused.When do you use P = Force * velocity = (mass * velocity^2) /time and when do you use P= W/t = 1/2* (mass*velocity^2)/time?

Answer 1

The power exerted by the electrical forces on a fragment of fiber is 8.0× 10^-5 Watts

Power and Energy or Work done

Power is the rate of doing work.

• Power = work done / time

Energy is the ability to do work.

Work done and energy are used interchangeably.

• Work done = Force × distance

In the example above, the energy possessed by the mass is kinetic energy.

Kinetic energy is the energy a body has by virtue of its motion.

• Kinetic energy, KE = 1/2 mv^2

Calculating kinetic energy of the body:

mass of the body = 0.04 g = 4.0 × 10^-5 kg

velocity of the body = 200mm/s = 0.2 m/s

Kinetic energy of the body = 1/2 × 4.0 × 10^-5 × 0.2^2

Kinetic energy of the body = 8.0× 10^-7

Thus, work done = 8.0× 10^-7 J

Calculating power exerted:

time taken = 10 ms = 0.01 s

Power = work done/ time

Power exerted = 8.0× 10^-7/0.01

Power exerted = 8.0× 10^-5 Watts

Therefore, the power exerted by the electrical forces on a fragment of fiber is 8.0× 10^-5 Watts

Learn more about about electrical energy and power at: brainly.com/question/60890