Equations (energy unit)

Question 1

power

Answer 1

P(Watts) = work done (J) / time (s)

P = W/t

Question 2

gravitational potential energy

Answer 2

GPE (J) = mass (kg) x gravitational field strength (N/kg) x height (m)

GPE = mgh

(the gravitational field strength on Earth is 10N/kg)

Question 3

What is all energy measured in?

Answer 3

joules (J)

Question 4

kinetic energy

Answer 4

KE (J) = 1/2 x mass (kg) x velocity² (m/s)

KE = 1/2mv²

Question 5

work done

Answer 5

W (J) = force (N) x distance moved (m)

W = Fd

Question 6

Rearrange the GPE equation so that:

a) m is the subject
b) g is the subject
c) h is the subject

Answer 6

a) m = GPE / gh
b) g = GPE / mh
c) h = GPE / mg

Question 7

Rearrange the KE equation so that:

a) m is the subject
b) v is the subject

Answer 7

a) m = 2KE / v²

b) v = √(KE / 1/2m)

Question 8

Rearrange the W equation so that:

a) F is the subject
b) d is the subject

Answer 8

a) F = W / d

b) d = W / F