Topic 1: Physics: Energy

What is the Rule of the Conservation of Energy?

The Conservation of Energy: The Principle of the conservation of energy says that it is impossible to create or destroy anything. It can only be changed from one form to another

What are the three main ways that energy can be stored?

Energy can be stored in 3 main ways:

• Chemical Potential-For Example: Batteries
• Elastic Potential-For Example: Springs
• Gravitational Potential-For Example: SkyDive

If its a Fuel then its Chemical Potential

If its Stretched then its a elastic potential

It its Dropped from a high height that its gravitational potential

What is Efficiency?

Efficiency is a measurement of how effective a device is at transferring energy

What is the Equation for Efficiency?

Equation for Efficiency:

Input Energy (Energy Supplied) = Useful energy transfered/ total energy supplied x100

How do you calculate Work Done?

Work Done= Force x Distance

What is the Equation for working out Power?

Power=Energy transfer/time

What is the Energy Transfer through a kettle?

Electrical ------> Sound+Thermal+Light+Kinetic

What is the Useful Energy for a lightbulb?

Electrical Energy------> Light+Thermal+Sound

For a Lightbulb, the energy transfer to light energy is the useful transer. The rest is 'wasted': it is eventually transfered to the surroundings, making them warmer. This 'wasted' energy eventually becomes so spread out that it becomes less useful. This is known as dissipation

What is the Efficiency of a light bulb if its useful energy is 200 and the total energy is 16000?

200/16000 x 100= 12.5%

What is the power of a light bulb when the energy transfer is 600J every 30 seconds?

Power=600/30=20W

What is thermal conductivivty?

Is a property of matter that either allows it to transfer heat readily from a hot to a cold object. Materials that have low conductivivty are usually known as insulators. For example: Wood, plastic etc. Materials with high themal conductivivty are known as conducters. For example: Copper, iron etc.

What is a Vacum and Why is its value 0?

A vacum is in space and a vacum has no particles within it it meaning the value of a vacum is 0. Vacum's are not a good thermal conductor because the value is 0, meaning Vacum's do not conduct anything