Chapter 1 : conservation and dissipation of energy

What is system?

an object or group of objects

What is a closed system?

1) one where no energy can escape to or enter from the surroundings

2) the total energy stays the same

State energy stores

1) chemical

2) elastic potential

3) magnetic

4) electrostatic

5) nuclear

6) thermal

7) kinetic

8) gravitational potential

State 4 ways energy can be transferred

1) heating

2) electricity

3) wave

4) mechanical

What is work done?

when an object is moved by a force

What is the unit of energy?

Joules(J)

What is one joule of work?

the work done when a force of 1N causes an object to move 1 m in the direction of the force

What did dissipate mean?

energy transferred to less useful stores

What all energy eventually ends up for transferred energy to

thermal energy store

what is lubrication?

a way of reducing unwanted energy transfer due to friction

What is streamlining?

a way of reducing energy wasted due to air resistance or drag in the water

what is power?

how much work is done( or how much energy is transferred) per second

What is the unit of power?

watts(W)

What is efficiency?

a measure of how much energy is converted usefully compared to how much energy is wasted

A motor is 30% efficient. What does it mean?

30% of the energy is usefully transferred and 70% is dissipated

how do we know which object has more efficiency by using efficiency value?

more useful output energy for the same input energy