P1 and P2 Test

?
  • Created by: kross2104
  • Created on: 02-10-18 13:27
What are the different types of energy stores?
Kinetic, Chemical, Gravitational potential, Magnetic, Elastic potential, Electrostatic, Thermal (internal) and Nuclear
1 of 41
How can energy be transferred from one store to another?
By; heating, work done by forces, work done when a current flows and electromagnetic radiation or Mechanical radiation (shock waves and sound)
2 of 41
How does the energy change when throwing an object?
After the object leaves your hand, it has a store of KINETIC energy. Once it reaches its highest point, the KINETIC energy transfers to GRAVITATIONAL POTENTIAL energy store. As you catch the ball, it has a store of KINETIC energy once again.
3 of 41
How does energy transfer when an object is dropped?
Before the object hits the ground, the object has a store of KINETIC energy. After the object hits the ground, the energy is transferred to THERMAL energy which is stored in the object or in the surroundings.
4 of 41
How does energy transfer when heating a resistor?
When the current flows through the resistor, energy os transferred by electrical work. Energy is transferred from the chemical store of the battery into the thermal store of the resistor and then into the thermal store of the surroundings.
5 of 41
How does energy transfer when a car accelerates?
A force on the car does work to accelerate the car. There is a store of chemical energy in the cars petrol. As the petrol burns, it transfers energy into kinetic energy which moves the car and also into the thermal energy store of the surroundings.
6 of 41
How is energy measured?
Energy is a quantity that is measured in Joules, J
7 of 41
How are large quantities of energy measured?
Kilojoules, kJ 1kJ=10^3J and Megajoules, MJ 1MJ=10^6J
8 of 41
How much energy is at the end of the process?
Energy is always conserved. You always have the same amount of energy
9 of 41
What is the principle of conservation of energy?
The amount of energy always remains the same, there are different stores of energy. In a process energy can be transferred from one star to another but it cannot be created or destroyed.
10 of 41
How do you calculate the kinetic energy of an object?
Kinetic energy = 0.5 x mass x speed^2
11 of 41
Calculate the kinetic energy stored in a vehicle of mass 500 kg moving at a speed of 12 m/s
Kinetic energy = 0.5 x 500 kg x (12 m/s)^2 = 36000 J
12 of 41
How do you calculate the amount of elastic potential energy stored in a stretched spring?
Elastic potential energy = 0.5 x spring constant x extension^2
13 of 41
How do you calculate gravitational potential energy?
GPE = mass x gravitational field strength x height
14 of 41
Calculate the increase in GPE of a 2 kg object raised through a height of 0.4 m when the gravitational field strength is 9.8 N/kg?
2.0 kg x 9.8 N/kg x 0.4 m = 7.8 J
15 of 41
How do you calculate the work done?
work done (J) = force (N) x distance moved in the direction of the force (M)
16 of 41
Calculate how much work was done by the builder when he pushed a wheelbarrow 5 meters with a force of 50N
work done = 50 N x 5.0m = 250J
17 of 41
What constitutes power?
Power is the rate at which energy is transferred or the rate at which work is done
18 of 41
What is the formula for power?
Power (W) = Work done (J) / Time (S) or P = E/T
19 of 41
What does the specific heat capacity measure?
The specific heat capacity of a substance is the energy needed to raise the temperature of 1kg of an object by 1 degrees celsius
20 of 41
What is the equation for calculating the specific heat capacity
Energy transferred ^E (J) = mass m (kg) x specific heat capacity c (J/kg*) x Temperature change ^0 (*C)
21 of 41
When is energy dissipated or wasted?
When it is stored in less useful ways. i.e we didn't want to produce it and we cannot recapture it do anything useful with it.
22 of 41
What is dissipation
Dissipation is the wasting and spreading out of thermal energy into the surroundings.
23 of 41
How can we slow down the process of thermal energy transfer in our houses?
Insulation, Carpets, Thick walls, Double glazing.
24 of 41
What is the thermal conductivity of a material?
A measure of how quickly the energy is transferred by conduction. e.g. metals have very high conductivities, brick and glass have low conductivities, but energy still flows through
25 of 41
Why do we reduce the dissipation of energy, for example in a car?
We increase the efficiency of the intended energy transfer. For example streamlining increases the amount of energy available to do work against resistive forces.
26 of 41
What is the equation to calculate energy efficiency?
Efficiency = Useful output energy transfer / Total input energy transfer
27 of 41
Calculate the efficiency of a steam engine using coal as its fuel. When the chemical store of the coal transfers 200 kJ of energy 24 kJ is done against resistive forces.
efficiency = 24 kJ / 200 kJ = 0.12 or 12%
28 of 41
How is energy transferred when an object falls and hits the ground?
Gravitational potential energy store transfers to kinetic energy which transfers to the surrounding in the form of thermal energy and sound waves
29 of 41
Describe the changes in energy stores in a torch lamp?
Chemical energy stored in the battery transfers to electrical current in the wires which is transferred to the surroundings as light waves and thermal energy.
30 of 41
How is energy transferred in a roller coaster?
As it climbs its gravitational potential energy store increases, this energy is transferred to kinetic energy store as the roller coaster descends, some of the energy is transferred to thermal energy store by air resistance and friction
31 of 41
How is energy transferred when bungee jumping?
Energy is transferred from the GPE store to the KE store as the jumper accelerates to the ground by gravity. The jumpers KE store decreases and the ropes EPE store increases.
32 of 41
A student of weight 300 N climbs on a platform that is 1.2 meters higher than the floor, calculate the increase in her GPE store?
Change in the objects GPE (J) = weight (N) x change in height (M) Therefore, GPE = 300 N x 1.2 m = 360 J
33 of 41
What is the GPE calculation for mass?
GPE change (J) = mass (kg) x gravitational field strength (N/kg) x change in height
34 of 41
What is useful energy?
The energy transferred to where it is wanted in the way which it is wanted.
35 of 41
What is wasted energy?
Energy that is not usefully transferred
36 of 41
A Motor transfers 10000 J of energy in 25 s. Work out its power
P (W) = E (J) /T (s) P=10000 J/25 s = 400 W
37 of 41
Which materials make good conductors?
Metals conduct energy better than non-metals, Copper is better than steel, glass is better than wood.
38 of 41
What materials make good insulators?
Materials that have low thermal conductivity. e.g. fibre glass.
39 of 41
What is infrared radiation?
All objects absorb and emit infrared radiation
40 of 41
What is black body radiation?
A perfect black body is an object that absorbs all of the radiation that hits it. It doesn't reflect or transmit any radiation.
41 of 41

Other cards in this set

Card 2

Front

How can energy be transferred from one store to another?

Back

By; heating, work done by forces, work done when a current flows and electromagnetic radiation or Mechanical radiation (shock waves and sound)

Card 3

Front

How does the energy change when throwing an object?

Back

Preview of the front of card 3

Card 4

Front

How does energy transfer when an object is dropped?

Back

Preview of the front of card 4

Card 5

Front

How does energy transfer when heating a resistor?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Physics resources:

Magnets
See all Physics resources »See all Energy resources »