Forces Flashcards
What is a force
It is a pull or push
A force cannot be seen, but the effect of it can be
What unit is force measured in
Force is measured in the Newton force can be measured with a spring balance or scale
Name all the different types of forces
Contact
field
gravitational
electrostatic
magnetic
What can happen if forces exerted on an object
Speeding up or slowing down deformation
rotation
Direction changes
object comes to a standstill
What are paired forces
Each object exerts a force of equal magnitude on the other object
the two forces are in opposite directions
non-contact or Field forces
These are forces that act over a Distance (action - over - a - distance.)
Contact forces
Forces that happen when an object touches another object
Name three examples of non-contact or Field forces
1 gravitational force
2 magnetic force
3 electrostatic Force
Name examples of contact forces
1 mechanical Force
2 applied force
3 friction Force
4 normal Force
5 tension force or tension
6 resistance
7 elastic forces in Springs
What is gravitational force and what are some examples of objects that attract each other
This is when objects attract each other without touching
the sun and the planet
the Earth and the Moon
the Earth and objects on the earth’s surface
What is mass
Mass is the amount of matter an object has
Mass is measured in kilograms
What is weight
Weight is the force an object exerts on another object
Explain magnetic forces
Magnets attract object that consists of iron, nickel or cobalt
if a material contains one of these properties it has magnetic properties
What do atoms consist of
Protons which is the positive charge and neutrons which is the Neutral charge both of these are in the nucleus
electrons are the negative charge and they occupy the space around the nucleus
Explain what an electrostatic force is
A force that charged object exert
When is an object negatively charged and when is it positively charged
An object is positively charged when it gives electrons away
and
it is negatively charged when it accepts electrons
What is needed for electrostatic forces to happen
Friction is needed
How do you charge an item
You can rub it
How is lightning formed
Particles and droplets in clouds rub and bump into each other and become charged
and
go to the bottom of clouds and transfer energy into the Earth
What is lightning
A massive spark of electricity
Some safety measures during lightning
1 avoid outdoor activities in bad weather
2 Take Shelter inside a building or vehicle
3 avoid trees, carports, convertible cars, motorbikes, Towers, fences, telephone poles and power lines
4 avoid using telephones and other electrical apparatus
5 don’t bath or shower
What are some safety measures if you are outside without shelter nearby
1 make your body size the smallest possible by squatting and putting your head between your knees
2 do not lie on the ground as the current can move through the ground and slow through your body
3 avoid trees fences and poles
4 if you are on a dam try to get to dry land as soon as possible and seek shelter
Name some facts about paired forces
They are always equal in magnitude
they act in opposite direction
act simultaneously on two different objects
What is the formula for calculating weight
Fg= W = mg
Fg = w represents weight in newtons
m represent mass in kgs
G represent gravitational acceleration
What are electrical cells
Cells are a source of electrical energy
What is a battery
More than one cell that are connected
Series circuit
The positive pole of one cell is connected to the negative pole of the following cell
Parallel circuit
This is a circuit which has more than one pathway for current
and
all the negatives poles are connected to one end and all the positive poles to the other end
What does a cell consist of
An electrolyte which contains positive and negative particles called ions and metal rods which serve as poles
What is an electrolyte
It is a solution which produces electricity
What are conductors
Substances that conduct an electrical current
and
offer a little resistance against the flow of charge
examples are copper,silver and iron.
What is a resistor
It is the component in a circuit that can control the energy transfer and the current and convert it into useful forms
Resistors are also known as poor conductors
What is resistance measured in
It is measured in ohm
What is the use of resistors
It takes flow in and collides the charges against the particles of the resistor and part of the electrical energy will be transferred to the particles of the resistor during the collision and the resistor will use this energy and converted it to heat, light or sound energy
What are the factors affecting/influencing resistance
The type of conductor
Set metals have less or more resistance than others for example
Copper golden silver have low resistance
whereas
tungsten nickel and chrome have high resistance
the length of conductor
The longer a conductor in the greater the resistance
thickness of conductor
The thicker a conductor the smaller that resistance
temperature
the hotter a conductor the greater the resistance
What is electrical current
It is charge(electrons) that flow
What is conventional current
Directions current is from the positive pole of the battery, through the circuit to the negative Pole
What is required for current to flow
A source of energy and a the circuit must be closed
What is the symbol for current and what is current measured with and what is the unit of measurement
The symbol for current design current is measured with an ammeter and the unit of measurement is ampere
Name two facts about an ammeter
An ammeter is always connected in series and has low resistance
What is potential difference and what is it measured in and with
Potential difference is the difference in potential energy over 2 points
it is measured with a voltmeter which is connected in parallel over a resistor or a cell/battery
unit is volts V
What are some effects of resistors
The total current of a sales/battery increases with each resistor being added in parallel
What two wires are connected to a household electricity meter
A neutral and a live wire
What measures how much energy is used in the household
The electricity meter
What does Earthed mean
Means that it is connected to the ground by a metal wire slash pipe
A 3 pin-plug has three wires what are the colors of those wire
There’s a brown live wire
a blue neutral wire
a striped yellow and green Earth wire
What is a fuse
A fuse is a small piece of metal that melts when there’s an overload and interrupts current so it cannot flow anymore
What is a circuit breaker
A circuit breaker is a switch(electromagnet) that trips as soon as the current becomes too large and the current is interrupted
Name the disadvantage and advantage of a fuse
A disadvantage of fuses that it has to be replaced and an advantage of a it is that it is cheap and easily available
Name the disadvantages and advantage of a circuit breaker
The disadvantage of a circuit breaker is that is expensive and the advantage of a circuit breaker is that it can just be switched on again
What is a lightning conductor
It is a metal rod with a shop end that is fixed to roofs/high points and another point that is planted into the ground it can also be connected to copper wire that is in the ground
What is the function of a lightning conductor
Charge of the lightning is concentrated on the shop point the charge is then conducting into the ground through the lightning conductor and copper wire with a lightning conductor a building or structure is Earthed
In what ways does electricity theft take place
Illegal connections
Fiddling with electricity meters
cable theft
Effects of electricity theft
Stability and qualities is influenced
can lead to power interruptions
Eskom cannot keep up with the increase in demand to provide electricity
big financial losses
people and animals can be shocked to death or seriously hurt
What is eskom responsible for
Generating electricity
transmission of electricity over long distance
distribution to the consumer
Benefits of nuclear power stations
There is little pollution
Constantly available
Safe if measures are followed
Effective electricity supply
Disadvantages of nuclear power
Danger of pollution if it is not strictly managed
relatively short lifespan of reactors danger of radiation
dangers of dumping of Radioactive waste
Limited dumping sites for waste
What are the units of measurements for energy time and transfer of electrical energy
Energy is Joules (J)
Time is seconds (s)
Transfer of electrical energy is watt(w)
What is measured in kilowatt
The amount of energy transferred
What is the formula for calculating the transfer of energy
P=VI
P-transfer of energy
V-is for potential difference which is a measured in volts
I is for current which is measured in
What does the formula for calculating the cost of energy
Cost of energy = kWhoursunit price
How many Watts are equal to a kilowattt
1,000 Watts is equals 1 kW
How many Joules are equal to a kilojoule
1000 Joules = 1 Kilojouled
In what unit is electric energy sold
Kilowatt hour (kWh)
