M3C3

Question 1

Define work done

Answer 1

The product of the force and the distance moved by the force

Question 2

What’s the formula(s) for work done work

Answer 2

W = f x d
W = F cos(θ)
W = work done (J)
f = force (N)
d = distance (m)

Question 3

One joule is defined as?

Answer 3

The amount of energy exerted when a force of one Newton is applied over a displacement of one meter

Question 4

What is the area under the graph equal to on a force-distance graph?

Answer 4

Area under graph = work done

Question 5

What’s the first law of thermodynamics

Answer 5

Energy cannot be created or destroyed. only transformed into another form

Question 6

What’s the formula for gravitational potential energy?

Answer 6

ΔGPE = mgh
ΔGPE = gravitational potential energy (J)
m = mass (kg)
g = acceleration due to gravity (m s^-2)
h = distance of the object from the ground (m)

Question 7

What’s the formula for kinetic energy?

Answer 7

KE = 1/2 mv^2
KE = kinetice energy (J)
m = mass (kg)
v = velocity (m s^-1)

Question 8

What do GPE and KE have in common?

Answer 8

They are both measured in joules
KE = 1/2 mv^2
ΔGPE = mgh
1/2 mv^2 = mgh

Question 9

What are the SI units for the joule?

Answer 9

1 J = 1 kg m^2 s^-2

Question 10

Define power

Answer 10

The rate of doing work

Measured in watts and has the units J s^-1

Question 11

Derive the equation P = Fv

Answer 11

P = e/t 
                 e = f x d
P = f x d / t  
                  d / t = v
P = Fv

Question 12

What’s the formula for power?

Answer 12

P = w / t
P = power ( w or J s^-2)
w = work done (J)
t = time (s)

Question 13

define efficiency

Answer 13

The ratio of the useful work performed to the total energy input

Question 14

Define waste

Answer 14

Energy that is used up in a transformation or process that we do not deem to be useful