physics
F=mg: A basketball has a mass of 1kg. calculate the force.
10N
F=mg: A small dog has a mass of 7kg. calculate the force
70N
F=mg: A car has a mass of 1200kg. calculate the force
12000N
F=mg: A pumpkin has a mass of 0.8kg. calculate the force
8N
Ep=mgh: A ball (mass = 0.5kg) is kicked onto a roof which is 3m high. calculate the energy potential
15J
Ep = mgh: A weight lifter lifts a 100 kg barbell from thr floor to a height of 2m. calculate the energy potential
2000J
Ep=mgh: A cat (mass = 4kg) climbs a tree to a height of 5m. calculate the energy potential
200J
Ep=mgh: A bird (mass = 0.30kg) flies up to a power line 4m higher than its current postion. calculate the energy potential
12J
Energy (%) = Useful energy÷total energy×100: A cyclist used aa total of 500J of energy. However due to friction only 350J contribute to the bikes motion. calculate the energy efficiency
70% efficent
Energy (%) = Useful energy÷Total energy×100: A toy car converted 100J of elastic energy into 75J of kinetic energy. calculate the energy efficiency
75% efficent
Energy (%) = Useful energy÷Total energy×100: A hydraulic lift uses 2000 joules of energy to raise a platform, but only 1800 joules are used in lifting. calculate rhe energy efficiency
90% efficent
Ek=1/2mv2: A cyclist and her bike have a mass of 70kg. Calculate her kientic enegy when she is riding at a speed of 5ms-1. calculate the kinetic energy
875J
Ek=1/2mv2: A ten-pin bowling ball (mass = 4.0kg) is bowled down the lane at a rate of 3.0ms-1. Calculate the ball's kinetic energy.
18J
Ek=1/2mv2: A car has a mass of 1300kg. Calculate the kientic energy of the csr when it's moving at a speed of 15ms-1.
146250J
Calculating velocity: A 2kg ball is moving with 49J of kinetic energy. Find the balls velocity.
v=7ms-1
W=Fd: What is this formula for?
Calculating power
W=Fd: How can this formula be rearranged to calculate force?
F=W÷d
W=Fd: How can this formula be rearranged to find the distance?
d=W÷F
P=W÷t: A wind turbine generates 300,000 Joules of energy every minute (60s) calculate the power
5000W
P=W÷t: A solar panel converts sunlight into 2000 joules of electrical energy in 4 seconds. calculate the power
500W
P=W÷t: A car engine does 600,000 joules of work in moving the car a certain distance in 6 seconds. calculate the power
1000W
P=W÷t: An electric heater uses 40,000 joules of energy to heat a room in 20 seconds. calculate the power
2000W
Q=mcT: A kettle is filled with 1.2kg of water at 15°C and heated until it reaches 100°C . caluclate how much energy has been added.
(c = 4200)
428400J
Q=mcT: Calculate the amount of heat energy required to change the temperature of ine litre (1kg) of water from 20°C to 100°C (c=4200)
336,000J
Q=mcT: A bucket is filled with 3kg of water at 20°C and is placed into a freezer until it reaches 0°C. Calculate how much energy has been removed from the water. ( c = 4200)
252,000J
P=VI: A lamp has a voltage of 120V and draws a current of 0.5A. Calculate the power of the lamp
60W
E=Pt: A 1500W electric heater left on for 30 minutes. calculate the energy
2,700,000J
R=V÷I: A circuit is connected to a 12V battery and draws a current of 2A. calculate the resistance of the circut
6 Ohm
what is kinetic energy?
kinetic energy is energy that moving objects have. this includes heat, energy, light energy, sound energy, and electrical energy.
What is kinetic energy measured in?
joules (J)
what is gravitational energy?
A form of energy that an object possesses or aquires due to its height
what is thermal energy?
thermal energy is when atoms and molecules vibrate within a substance. the faster they move the more energy they possess and the hotter they become
what is elastic energy?
A form of energy thaat is found in springy annd bouncy objects.
what is chemical energy?
it is when energy of chemical substances thaat is released when the substances undergo a chemical reaction and transforms into other substances
what can chemical energy be stored in?
in objects lile food or fuel
what are the types of potential energy?
elastic potenial energy, gravitational potential energy, chemical potential energy,
what is the difference between mass aand weight?
Mass is the amount of matter (measured in kg), weight is the force of gravity pulling you towards the centre off the earth. measured in n
describe what would happen to the kinetic energy if the car accelerates?
there will be more kinetic energy
what does the amount of kinetic energy depend on?
the mass and velocity
what is the source of energy the car engine transforms into kinetic energy?
chemical energy
a car begins to roll down a hill and reaches the bottom travelling at 50 kph. create a energy bar chart
E grav = E kinetic
A fully stretched rubber band is released and flies horizontlly. create an energy bar chart
E elastic = E kinetic
when does friction occur?
friction occurs when two sufaces move against each other, causing resistance.
what tyoe of energy is involved with friction?
resistsnce transforms the kinetic energy of moving objects into thermal energy due to vibration
grandad uses an old skateboard with rusty bearings. make an energy bar chart
E grav = E kinetic + E thermal
how can friction lead to energy loss in moving parts of a machine?
friction causes kinetic energy to turn into thermal energy which causes it to dissapate into its surroundings
A spring is compressed. create a work energy bar chart
W = E elastic
A footballer reciever a pass and without stopping the ball, passes to another player. her pass makes the ball move faster. Make a work energy bar chart
E kinetic + W = E kinetic
What are the particles doing in a solid?
the particles are tightly packed togther in a fixed shape. they are slowly vibrating
what are particles doing in a liquid?
the particles are moving more and loosely packed, this means the particles can slide past each other
what are particles doing in a gas?
the particles have a weak attractive force and are far apart, this is the point where the particles are vibrsting most
what is temperature?
temperature measures how hot or cold an object is
what is thermal energy? (compared to heat and temperature)
thermal energy is the total kinetic energy of all the particles in a substance
what is heat?
hest is the transfer of thermal energy from one object to another.
describe the difference between thermal energy and temperature
temperature is about how fast or slow the particles are moving, this tells us what the temperature is. thermal energy is about hiw many particles are there.
define thermal insulator
ibjects that dint have free electrons restricts the flow of kinetic energy preventing heat to move easily through the material
define thermal conductor
objects that posses free electrons that move around easily, letting kinetic energy flow through quickly
why is metal a good thermal conductor
metals have free electrons making it easy for heat to go from one particle to another
explain why air helps keep fish and chips warm
beacause air is a bad thermal conductor, it slows down the transfer of thermal energy from the hot food to the surrounding environment
how does a lava lamp work
when the lamp turns on the wax will start to melt and rise. this is because the oil is denser than the heated wax so it'll sink. but when the lamp is off the wax will cool down making it denser than the oil so it will sink to the bottom
what temperature is melting point?
0°C
what temperature is boiling poin?
100°C
what are the heating phases?
solid, melting, liquid, boiling, gas
what are the freezing phases?
gas, condensing, liquid, solidifying, solid
explain why current only flows through closed circuits?
when a circuit is open it creates a gap which prevents the current from flowing. so when it is closed, electrons are able to flow freely without going out the gap
definition of current
current os a flow of electrical charge carriers, usually electrons pr electron-deficient atoms
definition of voltage
an electrimotive force or potential differece expressed in volts
what is the symbol for current
I
what is the symbol for voltage
V
write a general statement about the voltage in a series circuit
the more voltage there is the more that is shared between the light bulbs
write a general statement about the voltage in a parallel circuit
the voltage in a parallel circuit is divided between each bulb
what is an incandescent light bulb?
it produces light by heating a filament until it glows, and it converts 10% of electrical energy into light the remaint 90% is lost as heat
what is a led light
it is a much longer lasting lgith bulb that converts 90% of electrical energy into light and only 10% is lost as heat
if a bulbs efficency is 4% discuss the energy transformations in this bulb
because the bulb is only 4% efficent the large amount of electrical energy must have been transformed into thermal energy
if the bulbs efficiency is 4% suggest hiw the circuit coulb be made more energy efficient. this may include replacing a component in the circuit
the circuit coulb be improved with a more efficent bulb. a bulb with a filament made from lower specific heat capacity would be better. the use of an LED bukb could produce the same amount of light using mucch less electrical energy