P2 Flashcards
Whenever two objects interact, the forces they exert on each other are?
Equal and opposite.
A number of forces acting at a point may be replaced by a single force that has the same effect on the motion as the original forces all acting together. This single force is called?
The resultant force.
A resultant force acting on an object may cause a change in its state of?
Rest or motion.
The velocity of an object is?
its speed in a given direction.
When a vehicle travels at a steady speed the resistive forces?
balance the driving force.
The greater the speed of a vehicle the?
greater the braking force needed to stop it in a certain distance.
The faster an object moves through a fluid the
greater the frictional force that acts on it.
Explain Terminal Velocity?
When the resultant force reaches 0 and the object is moving as fast as it will go.
A force applied to an elastic object such as a spring will?
result in the object stretching and generate elastic potential energy.
When an object speeds up or slows down, its kinetic energy
increases or decreases.
The momentum of an object is the product of
the object’s mass and velocity
When a force causes an object to move through a distance
work is done.
W is the work done in
in joules, J
F is the force applied in
newtons, N
Gravitational potential energy is the energy that an object
Generates the higher they move a away from the attracting object. (To a certain point.)
The current in an electric circuit depends on
the resistance of the components and the supply.
When certain insulating materials are rubbed against each other they become electrically charged. Negatively charged electrons are
rubbed off one material and onto the other.
Name three wires in a three-core cable?
Earth
Neutral
Live
How does RCCB stop you from getting electrocuted?
Sense the drop in the current and cuts the circuit
Radioactive decay can b triggered by certain chemical reactions
True or false?
True
What does a negative value for acceleration mean?
Deceleration
What happens to the gradient of the line on a distance time graph if the speed increases
Gradient increases
How can an objects travelling at a steady speed b accelerating?
By changing its direction
What part of a velocity time graph represents distance travelled?
Area between the line drawn on the x axis. (Area drawn in squares on the graph) and the shape made by the velocity per second,
What happens to an object moving at a steady speed if the resultant force on it is 0
The objects continues to move at a steady speed
When will a resultant force cause a deceleration
When the opposing force is acting in the opposite direction to the motion
What happens to the acceleration of an object as the resultant force increases?
The acceleration increases
What does Hooke’s law state?
The extension of a spring or wire is directly proportional to the force applied provided the limit of proportionality is not exceeded.
When is work done by a force?
Work is done whenever a force moves something over a distance.
What is the relationship between work and energy?
Work done = energy transferred
What is the unit of power?
W or watts
What is the unit of momentum?
Kgm/s or m/s
Why is a gymnast less likely to injure herself if she lands on a thick foam then if she lands on a hard floor?
A foam Matt increases the impact time. The hard floor does not absorb the impact as well.
In terms of electrons, how does an insulator become positively charged?
It loses electrons
What’s sort of force will there be between two negatively charged objects
A repelling force
What is an ohmic conductor?
A conductor that obeys ohms law
What is ohms law?
(volt, V) = current (ampere, A) × resistance (ohm, Ω )
V/I R triangle where i is amps
Explain the shape on a line on a current potential difference graph for a diode
It will stop at a certain value because it’s travelling the opposite direction.
A series circuit contains a variable resistor. If it’s resistance increases what happens to the potential difference (Volts/V) across it?
The potential difference across it increases
Where should an ammeter and a volt meter b placed in a circuit to measure the current through?
The ammeter should b placed in series and the voltmeter in parallel with the resistor/lightbulb
What is the potential difference of the mains supply?
230v
What is the frequency of mains supply
50 Hz
What is the peak voltage of mains supply?
+/- 325V
What colour is the neutral wire?
Blue
What does the cover on an earth wire look like?
It has green and yellow stripes
Why is the outer cover of a three pin plug made of plastic?
Plastic is a good electrical insulator
What is the unit of charge?
Coulomb, C
What is a circuit breaker?
An electromagnet switch that opens and cuts off the supply of the current is bigger than a certain value
What is the effect of pressure of the rate of radioactive decay
No effect
Background radiation?
Radiation that is around us all the time
What was Rutherfords Alpha particle scattering experiment
Firing alpha atoms at a thin metal foil
What happens the mass number of a nucleus when it emits a beta atom?
It stays the same
What happens to the atomic number of a nucleus when it emits a beta atom?
It goes up by 1
What happens to a atomic number of a nucleus when it emits an alpha particle
It goes down by 2
What happens to the mass number of a nucleus when it emits an alpha particle
It goes down by 4
Why is gamma radiation not deflected by electric and magnetic fields?
Gamma radiation is uncharged
What has happened to the number of atoms undergoing nuclear decay in a sample after three half lives has past
Decreased to one 8th of a original value
Why is alpha radiation unsuitable for monitoring the thickness of metal foil
Alpha radiation will not b able to pass through the foil
What is a fissionable isotope?
An isotope that can undergo the process of fission
Which two fissionable isotopes are used in nuclear reactors
Uranium
Plutonium
When does a chain reaction occur?
When each fission event causes further fission events
What is nuclear fission
The process of forcing two nuclei close enough together so they form a single larger nucleus
How can nuclei be made to come close enough to fuse
Can b brought about by making two light nuclei collide at very high speed
How long did it take for the temperature of the universe to fall enough so that uncharged atoms are formed
Millions of years
Why is a black hole black
Light can’t escape its gravity
When is a Black hole formed
After a supernova if the star’s mass is big enough
What is voltage (V)
Potential difference across a component in a circuit is measured using a voltmeter (Electrical pressure)
