Physics 2a Flashcards
How is an object given a static charge?
This is caused when certain insulating objects give/receive electrons. Wherever the electrons move is given a negative charge.
What is current?
The flow of electrons around a circuit. Measured in Amperes (A).
What is potential difference?
The driving force around a circuit. Measured in Volts (V)
What is resistance?
Anything that slows the current in a circuit. Measured in Ohms (Appropriate Greek symbol).
What is work done?
Energy transferred.
What is the relationship between kinetic energy and potential difference?
Kinetic energy lost is potential energy gained.
What is work done to an elastic object stored as?
Elastic potential energy.
What is an elastic objects limit of proportionality?
The maximum length that it can be stretched before it won’t go back to its original shape.
What are the roles of ammeters and voltmeters?
To measure current and potential difference.
Why does resistance increase with temperature?
Some of the electrical energy is converted into heat energy. This causes ions in the conductor to vibrate more and in so making it harder for charged electrons to get through, reducing the current.
What is the role of an LED?
Give 2 uses.
They emit light when current passes through them in a forward direction. They indicate presence of current in a circuit. Uses: traffic lights, remote controls and digital clocks.
What happens in an LDR?
When light increases, the resistance decreases.
What is a series circuit?
All components are in a line, end to end between the positive and negative power supply.
What is a parallel circuit?
Each component is separately connected to the positive and negative of the power supply. If you remove one, you will hardly make a difference because the circuit is still complete.
What is represented by a curve on a VT graph?
A change in acceleration.
Why is velocity different to speed?
Velocity is speed with a direction.
What is represented by a flat on a DT graph?
The vehicle is stationary.
What is gravity?
The force that holds you on earth, pulling you into the centre.
What is weight?
The force of gravity that pulls you into the centre of the earth.
What is mass?
The amount of ‘stuff’ inside your body.
What is the gravitational field strength of the earth?
10 N/Kg.
What is meant by the term ‘resultant force’?
The overall force on an object or point.
What is the movement of an object if the resultant force is:
a) Zero (on a stationary point)?
b) Zero on a moving point?
c) Higher than zero?
a) Stationary
b) Moving at a constant velocity
c) Acceleration.
What happens to forces when two objects meet?
The forces they exert are equal and opposite.
What is friction?
A force that acts against the driving force.
What is terminal velocity?
When the frictional forces and acceleration forces on a falling object are equal.
What are the factors affecting stopping distance?
- Tyre condition
- Road condition
- Whether or not the road is wet/icy
- Your speed
- Your level of alertness.
What are the two different distances that make up stopping distance?
Thinking & braking distance.
What happens to momentum in a collision?
It is conserved.
How to brakes slow cars down?
- By converting kinetic energy into heat and sound energy.
- In regenerative braking systems, the brakes put the car motor into reverse, slowing the car down. At the same time, kinetic energy is turned into electrical energy and stored.
Give 3 safety features of cars
- Crumple zones
- Side impact bars
- Seat belts
- Air bags.