Work done and energy (5.1-5.2)

Question 1

What is the equation for work done?

Answer 1

Work done(J / Nm) = Force(N / Kgms^-2) x Distance moved(m)

Question 2

What is work?

Answer 2

Work is the product of force and the distance moved in the direction of the force, measured in Joules

Question 3

What else can work done be referred as?

Answer 3

Energy transferred

Question 4

If I was to drop my phone which weighs approximately 250g at a height of 1.71m from the ground, what would the work done be?

Answer 4

W = Fx
~We have to find the force~
Weight = mg
~Don’t forget to convert to SI units~
Weight = 0.25 x 9.81 = 2.4525
~Sub back into the equation~
Work done = 2.4525 x 1.71 = 4.193…
Work done = 4.19J (3.s.f)

Question 5

How do you find the work done on an object when the force is acting at an angle different from the direction of movement?

Answer 5

Find the component of the force in the direction of the motion then substitute that into the equation.
e.g. If the direction of motion is horizontal, then find the force acting horizontally.

Question 6

What is energy?

Answer 6

Energy is a scalar quantity that is the capacity for doing work. It is a scalar quantity with a magnitude but not direction. The SI unit for energy is Joules which is the same for work done.

Question 7

What does ‘potential’ mean?

Answer 7

Potential is often used in physics to mean ‘hidden’ or ‘stored’

Question 8

What is the principle of conversation of energy?

Answer 8

The total energy of a closed system remains constant.
Energy cannot be created nor destroyed, only transferred from one form to another.

Question 9

What are the differenet forms of energy?

Answer 9

Kinetic energy
Gravitational potential energy
Chemical energy
Elastic potential energy
Electrical potential energy
Nuclear energy
radiant(or electromagnetic) energy
sound energy
internal(heat or thermal) energy