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Science junior cycle flash cards > Physics junior cert > Flashcards

Physics junior cert Flashcards

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1
Q

What is the formula of acceleration?

A

The change in speed divided by the time taken for the change
Final speed - first speed Change in time
m/s​2

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2
Q

What is the formula of velocity?

A

The speed of an object and the direction in which it is travelling
Distance Time
(In a certain direction)
m/s in a certain direction e.g north, south

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3
Q

What is the formula of speed?

A

The distance travelled by an object in one
unit of time
Distance m/s Time

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4
Q

What is the formula of density?

A

Mass
Volume
g/cm3​

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5
Q

What is the formula of mass?

A

Density x Volume g

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6
Q

What is the formula of volume?

A

Mass cm3​ Density

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7
Q

How do you measure density?

A

● Measure the mass of the object with a mass balance
● Measure the volume of the object
● Divide the mass by the volume of the object
Measuring the density of an regular/irregular solid shape
● Measure the mass of the object
● Pour water into the overflow can until it overflows
● Let the excess water overflow into a graduated cylinder
or a sink and pour that away
● Place the object into the overflow can and the water
levels will rise
● The rising water will cause the can to overflow again
and this excess water will be collected in the graduating
cylinder
● Read the graduated cylinder to see the volume of the object
● Divide the mass by the volume of the object

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8
Q

What is floatation?

A

● A solid will float on a liquid if it is less dense than the liquid
● A liquid will also float on another liquid if it is less dense

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9
Q

What is force?

A

● Force ​refers to something that causes an object to accelerate
● Unit is the Newton (N)
● Measured with a newton-meter
● Objects cannot move by themselves.
● They must be pushed and pulled.
● Force is the thing that causes the body to be pushed and pulled.
● Force causes the body to accelerate, decelerate and velocity (stop or change direction)

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10
Q

What are the types of force?

A 
● Weight
● Magnetic
● Electric
● Friction
● Push
● Pull
● Weight
● Friction
● Tension
● Reaction
● Stretching
● Twisting
● Compression ● Magnetic
● Electric
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11
Q

What is weight?

A

● The force of gravity on a body is known as weight
● Weight is measured in newtons
● Weight is not the same as mass
● Weight (N) = mass (in kg) x 10

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12
Q

What is friction?

A

● A force that opposes the sliding motion between two objects in contact
● Advantages of friction
➢ Allows us to pick things up
➢ Lubrication - oil is used in engines ➢ Tyres on cars prevent skidding
➢ Friction holds nails in pieces of wood
● Disadvantages of friction
➢ Friction can wear away surfaces in contact such as brake pads on bikes ➢ Blisters on your ankle due to new shoes is a result of friction
➢ Friction wastes fuel

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13
Q

What is hookes law?

A

● The extension of a spring is directly proportional to the force that is stretching it
● Exceeding the elastic limit means that the force that was used to stretch the spring is too large and the spring loses its elasticity (does not return to it’s original shape)

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14
Q

What is the law of the lever?

A

● When a lever is balanced, the sum of the clockwise moments equals the sum of the anticlockwise moments
● Force x Perpendicular distance from the fulcrum to the force = Force x Perpendicular distance from the fulcrum to the force

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15
Q

What is centre of gravity?

A

● A point in the object through which all the weight of the object appears to act
● When an object is balanced and it stays still, the object is in
equilibrium
● Stable equilibrium ​refers to when it will return to the same
position when pushed - the fulcrum is above the centre of
gravity
● Unstable equilibrium ​refers to when it will not return to the
same position when pushed - the fulcrum is below the centre
of gravity
● Neutral equilibrium ​is when it will return to a similar position
when pushed

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16
Q

What is stability and how can you improve it?

A

Stability
● An object will topple over if the weight of the object acting through the centre of gravity passes outside the base of the object

Improving stability
● Widening the base of the object
● Lower the centre of gravity of the object

17
Q

What is pressure?

A

Pressure = ​Force over Area
● Force is measured in Newtons (N)
● Area is measured in either cm2​ ​ or m2​
● Unit or pressure is Nm​2​ or Ncm2​
● If Nm2​ ​, it can also be written as Pascal (Pa)

18
Q

What is atmospheric pressure?

A

● The force of gravity pulls the gases in the atmosphere into the Earth
● These gases exert forces, which results in atmospheric pressure
● Atmospheric pressure acts equally in all directions and our body balances this by
exerting pressure pushing out
● Atmospheric pressure increases as the distance from the sea level increases e.g at the
top of a mountain, the pressure is greater

19
Q

What is pressure in liquid?

A

● Pressure varies with depth in a liquid
● Pressure increases as the depth of water increases
● Pressure decreases as the depth of water decreases

20
Q

How do you measure pressure?

A

● Pressure is measured with various instruments
● Barometer
● Pressure Gauge
● Altimeter

21
Q

What is energy and what are the different types of energy?

A 
Energy
● The ability to do work
● Measured in Joules (J)
● Kinetic e.g waves
● Potential e.g in a spring
● Sound e.g guitar strings
● Heat e.g thermometer
● Chemical e.g batteries
● Electrical e.g electric car
● Magnetic e.g magnetic trains
● Solar e.g Crook’s radiometer
● Nuclear e.g nuclear power station
22
Q

What is the difference of nuclear fission and nuclear fusion?

A

Nuclear Fission
A large nucleus is divided into two equal parts. However, radioactive substances are released which can be harmful to humans. Radiation has the ability to kill cells and induce some forms of cancer

Nuclear Fusion
Light nuclei are forced to join together and this produces nuclear fission energy

23
Q

What is heat and what is it measured in?

A

● Heat ​is a form of energy
● Heat is measured in Joules (J)
● Heat is different to temperature

24
Q

Explain heat transfer!!!

A

The method by which heat travels from particle to particle through a solid
Convection
● The transfer of heat through a liquid or gas when the particles of the liquid or gas move and takes the heat with them
Radiation
● The rapid transfer of heat from a hot object without needing a medium
Insulator
● A substance which does not allow heat to flow through it easily
To Show the Transfer of Heat by Conduction and to Compare the Conductivity of Various Substances
● The match fell off the metal copper first because the wax melted at the end
● They match fell off the metals in the following order (from first to last) : copper, aluminium, brass, iron and steel
● Steel is the best insulator and copper is the worst insulator
● Copper is the best conductor and steel is the worst conductor

25
Q

Explain latent heat and temperature and heat

A

Temperature
A measure of the level of how hot or cold an object is
Measured in degrees Celsius
Heat
Heat is a form of energy Measured in Joules

Latent heat
● The heat taken in or given out when a substance is changing state without changing temperature
● All of the heat energy is being used to loosen chemical bonds

26
Q

What is light?

A

Light​ is a form of energy

27
Q

What is a magnetic force?

A

Magnetic force ​is the force of attraction or the force of repulsion between two magnets

28
Q

What is a current ?

A

Current electricity ​is the flow of electrons through a circuit from the negative terminal to the positive terminal of a battery
Current (I)
● Current refers to the actual electrons flowing
● Ammeter measures the amount of current flowing
● The unit is Amp
● The unit symbol is A

29
Q

What is a conductor?

A

In ​conductors, ​electrons are free to flow through the object. They were loosely attached to their
atom and became free easily to flow along the conductor.

30
Q

What is resistance?

A

Resistance (R)
● Resistors control the amount of electrons flowing through a conductor
● The unit is the Ohm
● The unit symbol is Ω
● Resistors are used to provide heat, light or to return the current of a circuit
● A rheostat is a variable resistor (a resistor that can change the resistant)
● If the resistance increases, the current decreases
● Examples: volume switch on radios, dimmer switches and light bulbs

31
Q

What is Ohms law???

A 
Ohm’s Law
● V= I x R
● Voltage = Current x Resistance
● Ohm’s Law states that voltage is directly proportional to the current
P = V x I
32
Q

What is a resistor?

A

Resistor
● Contains a material that can resist the flow of electricity
● Can be used to reduce voltage in a current

33
Q

What is a diode?

A

Diode
● A device that allows current to flow in one direction only
● Forward bias is when the diode is in a circuit and the current
flows - the cathode is connected to the negative terminal and
the anode is connected to the positive terminal
● Reverse bias is when the diode is in a circuit and the current
does not flow - the cathode is connected to the positive terminal and the anode is connected to the negative terminal

34
Q

What is an LED?

A

LED
● LED stands for Light Emitting Diode
● LEDs are diodes that produces light when current passes through them
● Must be connected in forward bias to emit light
● Must be in a circuit with a resistor to prevent overheating
● LEDs require a small amount of current compared to ordinary bulbs

35
Q

What is a LDR?

A

LDR
● LDR stands for Light Dependent Resistor
● The resistor changes its resistance depending on the light intensity
● They are used in street lights

36
Q

What is current electricity?

A

Current electricity ​is the flow of electrons through a circuit from the negative terminal to the positive terminal of a battery

37
Q

What is potential difference?

A

Potential Difference/Voltage/Emf (Electron Moving Forces) - (V)
● Potential difference provides energy to push electrons around the circuit
● Battery is the source of power
● Voltmeter measures the potential difference between any two points on a circuit
● The unit of measurement is the Volt
● The unit symbol is V

38
Q

What is current?

A

Current (I)
● Current refers to the actual electrons flowing
● Ammeter measures the amount of current flowing
● The unit is Amp
● The unit symbol is A

39
Q

What is resistance?

A

Resistance (R)
● Resistors control the amount of electrons flowing through a conductor
● The unit is the Ohm
● The unit symbol is Ω
● Resistors are used to provide heat, light or to return the current of a circuit
● A rheostat is a variable resistor (a resistor that can change the resistant)
● If the resistance increases, the current decreases
● Examples: volume switch on radios, dimmer switches and light bulbs

Science junior cycle flash cards (3 decks)

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