MOCKS Flashcards
ENERGY STORES
NCMGKTEE
Difference between conduction, convection and radiation
conduction and convection both rely on particles
radiation relys on electromagnetic waves
Work done
force acting on an object causing it to move
Power
how quickly work is being done
Types of non-renewable forms of energy production
wind turbines
geothermal energy
wave energy
solar cells
In addition to power input, light bulbs should also be labelled with the rate at which they emit visible light.
Suggest why.
bulbs also transfer thermal energy
the efficiency of the light bulb
also needs to be considered
The muscle power of each volunteer was measured five times.
The highest muscle power reading was recorded instead of calculating an average.
Suggest why.
performance decreases due to tiredness
maximum height reached is a
better indicator of maximum
muscle power
performance may improve with practise
Engineers have developed a way of charging electric cars while they are driving along box the road.
Coils of wire buried under the road transfer energy to the car’s battery as the car is passing over the coils.
Suggest two advantages of using this method to charge electric cars compared with plugging them into the mains electricity supply.
fewer cells needed in car
can charge more cars at the same time
When electric cars are not being driven, energy stored in their batteries could be used to meet sudden peaks in electricity demand.
Suggest how.
when cars are plugged in
energy in batteries can be transferred back to the national grid
Explain why contamination of the inside of the human body by a radioactive material that emits alpha radiation is highly dangerous
alpha radiation is highly ionising
causing an increased risk of
cancer/ organ failure / mutation of DNA
until the radioactive material is
removed
As the person moves down the zip wire her increase in kinetic energy is less than her decrease in gravitational potential energy.
(work done against) air resistance
causes thermal energy to be transferred to surroundings
Different people have different speeds at the end of the zip wire.
Explain why.
different people have different
surface areas
so would be affected by air
resistance differently
Explain how the zero error may be corrected after readings had been taken from the balance
record the value of the zero error when there is nothing on the balance
take this away from each reading
The ammeter used in a circuit had zero error.
What does a zero error mean in a circuit?
ammeter displays a reading
when not connected (to a circuit)
Give two environmental advantages of using a gas-fired power station to generate electricity compared with using a coal-fired power station.
- no sulfur dioxide released
- doesn’t cause acid rain
- no particulates released
- doesn’t cause global dimming
- less carbon dioxide released
(per kg of fuel burned) - less global warming
- no solid waste
- gas mining is less destructive
than coal minin
Explain how the process of nuclear fusion leads to the release of energy.
lighter nuclei join to form heavier
nuclei
some of the mass (of the nuclei)
is converted to energy
Explain the advantage of the radioactive waste having a shorter half-life
activity decreases quickly
risk of harm decreases quickly
At the bottom of the slide, all riders and their sleds have approximately the same speed.
Explain why.
all GPE converted to KE
GPE = mgh
KE = 1/2mv^2
mgh = 1/2mv^2
(mass cancels on both sides)
gh = 1/2v^2
2gh = v^2
square root of 2gh = v
therefore speed at bottom is independent to mass (as is dependent on gravitational field strength and height (mass is the only one removed)
slight variations in speed due to variations in air resistance
When the kettle was switched on the temperature of the water did not immediately start to increase.
Suggest why.
the heating element of the kettle takes time to heat up
Mean = 15.7Ω
The student thought that taking a fourth reading would improve the precision of the results.
The fourth reading was 16.2 Ω.
Explain why the student was wrong.
precise results show little variation
the 4th result was further away from the mean than the other values
Explain why adding resistors in parallel decreases the total resistance.
multiple paths for charge to flow
total current is greater (for the
same potential difference when
more resistors are added)
as current is shared by all resistors
How to prove something is inversely proportional - R decreases as n increases
n ∝ 1/R
nR ∝ 1
(1 means constant)
so do 2 values and multiply them and they should be the same
e.g.
6 x 8 = 48
2 x 24 = 48
How to prove something is directly proportional - R increases as n increases
n ∝ R
n/R ∝ 1
(1 is constant)
so find 2 values that when divided by each other == to the same
An electrician replaced the switch.
The electrician would have received an electric shock unless the circuit was disconnected from the mains supply.
Explain why
one wire in the switch is live (and has p.d. of 230v)
the electrician is earthed (as he has a p.d. of 0v so current would flow through the path of least resistance - which is him)
(so) there will be a (large) potential difference between the live wire and the electrician
The temperature of the helium in the balloon was increased.
The mass and volume of helium in the balloon remained constant.
Explain why the pressure exerted by the helium inside the balloon would increase.
particles have more kinetic energy
increases number of collisions of particles with the walls of the balloon per second
greater force exerted in the collisions
greater force exerted on the same area
The negatively charged student touches a metal tap and receives an electric shock.
Explain why
The tap is earthed
there is a potential difference between the student and the tap
electrons are transferred from the student to the tap
Some carpets have thin copper wires running through them. The student is less likely to receive an electric shock after walking on this type of carpet.
Suggest why
copper is a conductor (so has low resistance)
so any charge that flows through will be immediately transferred to the copper (as opposed to the carpet which is an insulator with high resistance)
so there is no build-up of charge
Suggest one reason why the Banana Equivalent Dose may help the public be more aware of radiation risks
people are able to compare a
radiation risk to the radiation dose from eating a banana
Risk of high current and prevention
may cause burns to skin
use a lower current
The maximum speed this cyclist can travel on a level road is 14 m/s.
How does cycling uphill affect the maximum speed of this cyclist?
Explain your answer.
He has the same power output (constant)
however, as it is uphill, work is done against gravity (that’s trying to push him back down)
this lowers the maximum speed of the cyclist
In an ohmic conductor
current through a component = potential difference across component
provide temperature remains constant
In a series circuit
potential difference is shared in
proportion to the resistance
The smoke alarm would not work with a radiation source that emits beta or
gamma radiation.
Explain why.
beta and gamma radiation will penetrate smoke (not stopped by smoke)
detector will not detect any change
Explain the ideal properties of a radioactive source for use in medical diagnosis
short half-life or half-life of a few hours
* (short half-life means) less damage to cells / tissues / organs /
body
* low ionising power
* (low ionising power means) less damage to cells / tissues /
organs / body
* highly penetrating
* (highly penetrating means) it can be detected outside the body
