5: Work, Energy, Power

Question 1

Work done, W

Answer 1

Work done is defined as the product of force and the displacement in the direction of the force.

Question 2

Work done, W equation

Answer 2

W = F s cosθ

Question 3

Work done by gas formula

Answer 3

W = P (V₁ - V₂)

Question 4

(Work done by gas) Force equation

Answer 4

F = PA

Question 5

Energy

Answer 5

Energy is defined as the ability to do work.

Question 6

Principle of Conservation of Energy (CoE)

Answer 6

The CoE states that energy can neither be created nor destroyed in any process. It can be transferred from one form to another, and transferred from one body to another, but the total amount remains constant.

Question 7

Kinetic energy, Ek

Answer 7

Kinetic energy is the energy of a body due to motion.

Question 8

Kinetic energy, Ek formula

Answer 8

Ek = 1/2 m v²

Question 9

Work-Energy Theorem

Answer 9

The Work-Energy Theorem states that the net work done by external forces acting on a particle is equal to the change in kinetic energy of the particle.

W = ▵Ek

Question 10

Gravitational potential energy, Ep

Answer 10

Gravitational potential energy is the energy of a body due to its position.

Question 11

Gravitational potential energy, Ep formula

Answer 11

Ep = mgh

Question 12

Elastic potential energy, EPE formula

Answer 12

EPE = 1/2 F x = 1/2 k x²

Question 13

Power, P

Answer 13

Power is defined as the rate of doing work.

Question 14

Average power, <p></p>

Answer 14

The average power delivered by a working force is defined as the total work done divided by the total time interval.

<p> = W / t</p>

Question 15

Power, P formula

Answer 15

P = W / t = Fv

Question 16

Principle of Conservation of Mechanical Energy (PCME)

Answer 16

When work is done by conservative forces, the total mechanical energy of a system is conserved. In other words, the gain in KE is equal to the loss in PE for the conservative system and vice versa.