P1-Energy

?
  • Created by: Bootsy
  • Created on: 07-03-18 17:20

Energy Stores and Systems

1. Thermal Energy Stores

2. Kinetic Energy Stores

3. Gravitational Potential Energy Stores

4. Elastic Potential Energy Stores

5. Chemical Energy Stores

6. Magnetic Energy Stores

7. Electrostatic Energy Stores

8. Nuclear Energy Stores

Energy is transferred mechanically, electrically, by heating or by radiation.

When a system changes, energy is transferred. It can be transferred into or away from the system, between different objects in the system or between different types of energy stores. Closed systems are where neither matter nor energy can enter or leave. The net change in the total energy of a closed system is always zero.

Kinetic and Potential Energy Stores

Kinetic= Anything that moves. Energy is transferred to this store when an object speeds up or slows down. The kinetic energy store depends on the objects mass and speed. The greater its mass and the faster it's going, the more energy there will be.

KINETIC ENERGY= 1/2 X MASS X VELOCITY(SQUARED)

Gravitatonal= lifting an object in a gravitational field requires work. This causes a transfer of energy to the gravitational potential energy store of the raised object. The amount of energy in a gpe store depends on the objects mass, height and strength of the gravitational field.

GPE= MASS X GRAVITATIONAL FIELD STRENGTH X HEIGHT

When something falls energy from its gravitational potential energy store is transferred to its kinetic energy store.

For a falling object with no air resistance.... ENERGY LOST FROM THE GPE STORE=ENERGY GAINED IN THE KINETIC ENERGY STORE.

Elastic= Stretching or squashing an object can transfer energy from its elastic potential energy store

ELASTIC POTENTIAL ENERGY= 1/2 X SPRING CONSTANT X EXTENSION(SQUARED)

Specific Heat Capacity

More energy needs to be transferred to the thermal energy store of some materials to increase their temperature than others. Materials that need to gain lots of energy in their thermal energy stores to warm up also transfer loads of energy when they cool down again.

Specific Heat Capacity= The amount of energy needed to raise the temperature of 1kg of a substance by 1oc.

CHANGE IN THERMAL ENERGY= MASS X SPECIFC HEAT CAPACITY X TEMP CHANGE

PRACTICAL....A block of material with two holes in it. Measure the mass of the block then wrap it in an insulating layerto reduce the energy transferred from the block to the surroundings. Insert the thermometer and the heater. Meaure the temepratre of the block and set the potential difference of the power supply to 10v. Turn it on and start the timer. The current does work on the heater causing it to heat up. As the block heats up take reading of the temperature. Using the measurement of the current, potential difference you can calculate the power supplied to the heater.

Conservation of Energy and PowerPrinciple= "Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed."

When energy is transferred

Comments

No comments have yet been made