Chapter 13: Work, Energy and Power.

Question 1

What is the formula for Work Done?

Answer 1

Work Done = Force x Distance.

Question 2

What Units does Work Done have?

Answer 2

Joules (J).

Question 3

What Units does Force have?

Answer 3

Newtons (N).

Question 4

What Units does Distance have?

Answer 4

Metres (m).

Question 5

What is the formula for Power involving Work Done and time?

Answer 5

Power = Work Done/ Time taken.

Question 6

What Units does Power have?

Answer 6

Watts (W).

Question 7

What Units does Time have?

Answer 7

Seconds (s).

Question 8

What are the formulas for Power?

Answer 8

• Power = Force x Velocity.
• Power = Work-done/ Time.

Question 9

What is the formula for Gravitational Potential Energy?

Answer 9

GPE = mgh.

Question 10

What Units does Energy have?

Answer 10

Joules (J).

Question 11

What Units does Mass have?

Answer 11

Kilograms (kg).

Question 12

What Units does Acceleration due to Gravity (g) have?

Answer 12

Metres per second squared (m/s²).

Question 13

What Units does Height have?

Answer 13

Metres (m).

Question 14

What is the formula for Kinetic Energy?

Answer 14

KE = 1/2 mv².

Question 15

What Units does Velocity have?

Answer 15

Metres per second (m/s).

Question 16

What is the equation for Newtons Second Law?

Answer 16

F = ma.

Question 17

What is the conservation of energy principle?

Answer 17

Kinetic Energy (KE) gained = Gravitational Potential Energy (GPE) Lost. Vice versa.

Question 18

What is the formula for the Work-Energy Principle?

Answer 18

Work Done = Change in GPE + Change in KE.

Question 19

What is the formula for Hooke’s Law?

Answer 19

T = λx/ l (natural length).

Question 20

What does the ‘x’ mean in Hookes Law and what is its Units?

Answer 20

Extension - Metres (m).

Question 21

What does the ‘l’ mean in Hookes Law and what is its Units?

Answer 21

Natural/ Unstretched Length - Metres (m).

Question 22

What is the formula for Stiffness (k)?

Answer 22

k = λ/ l (natural length).

Question 23

What is the formula for Elastic Potential Energy?

Answer 23

EPE = λx²/ 2l.

Question 24

What are the Units of the Modulus of Elasticity (λ)?

Answer 24

Newtons (N).

Question 25

If a string or spring goes beyond its elastic limit what happens?

Answer 25

It becomes permanently deformed and Hooke’s Law won’t work as it won’t return to its original shape.

Question 26

What is the equation for Work Done by all external forces?

Answer 26

Work Done = change in GPE + change in KE + change in EPE.