Work Done

Question 1

Work done =

Answer 1

Force x displacement in direction of force

Question 2

If a force is acting at an angle work done =

Answer 2

Fcos(angle)s

Question 3

Kinetic energy =

Answer 3

1/2 mass x velocity^2

Question 4

Gravitational potential energy =

Answer 4

Mass x gravitational field strength x height

Question 5

Define a joule

Answer 5

Work done by a force of 1 newton moving the point of application a distance of 1 metre

Question 6

What is the conservation of energy?

Answer 6

Energy cannot be created or destroyed only transferred into other forms

Question 7

Define power

Answer 7

Rate of doing work

Question 8

Power =

Answer 8

Work done or energy
——————————
Time

Question 9

Power =

Answer 9

Force x velocity

Question 10

Efficiency =

Answer 10

Useful energy output
——————————x100
Total energy output

Can also do the same for power as power is the rate of energy transfer

Question 11

Derive P=fv

Answer 11

P=W
   ——
      t
 =Fs                   s
   ——             —— = velocity
      t                   t
 =Fv

Question 12

Derive KE = 1/2 mv^2

Answer 12

W=Fs               (F=ma)
W=mas
Using suvats assuming u=0
v^2=2as
as=v^2
      ——
         2
W=mv^2
     ———
         2
   =1/2mv^2

Question 13

Derive GPE=mgh

Answer 13

W=Fs
F=mg as the force is equal to the weight of the object
And s is the vertical height that the object is lifted

So GPE=mgh