Physics Paper 2 Notes
Physics Basics
Work, Energy, & Power
Energy: Something that is needed to make things happen or to change something.
Work Done: A measure of the energy transferred when a force acts through a distance.
o Work done is measured in Joules.
o 𝑾𝒐𝒓𝒌 𝒅𝒐𝒏𝒆 (𝑱) = 𝑭𝒐𝒓𝒄𝒆 (𝑵) 𝑿 𝑫𝒊𝒔𝒕𝒂𝒏𝒄𝒆 𝒎𝒐𝒗𝒆𝒅 𝒊𝒏 𝒕𝒉𝒆 𝒅𝒊𝒓𝒆𝒄𝒕𝒊𝒐𝒏 𝒐𝒇 𝒕𝒉𝒆 𝒇𝒐𝒓𝒄𝒆 (𝑴)
o You can measure that work done by recording the size of the force and the distance moved in the
direction of the force. Having recorded these values, multiply them together to find the value for the
work done.
Power: The rate at which energy is transferred [the rate of doing work].
o When energy is being transferred by forces, then power is also the rate of doing work.
o Power is measured in Watts => 1 Watt = 1 Joule/1 second.
1 horsepower = 746 Watts.
𝑾𝒐𝒓𝒌 𝒅𝒐𝒏𝒆 (𝑱) 𝑬𝒏𝒆𝒓𝒈𝒚 (𝑱)
o 𝑷𝒐𝒘𝒆𝒓 (𝑾) = OR 𝑷𝒐𝒘𝒆𝒓 (𝑾) =
𝑻𝒊𝒎𝒆 𝒕𝒂𝒌𝒆𝒏 (𝑺) 𝑻𝒊𝒎𝒆 𝒕𝒂𝒌𝒆𝒏 (𝑺)
Changing the energy of a system:
1. Work done through forces: A body can be lifted through a vertical height by a force. This will
increase the store of GPE.
2. Electrical equipment: A cell in a circuit provides a potential difference so that components in the
circuit can transfer energy into other forms, such as TE.
3. Heating a material: Supplying TE to a system will increase the KE of the particles in the material. Its
temperature will increase if it is not changing state.
Interacting Forces
Pairs of forces can interact at a distance or by direct contact.
Contact Forces: The forces between objects that are touching.
In each case there is an interaction pair of forces that act in opposite directions.
The forces can be represented by vectors.
Tension, drag, and friction are all contact forces.
Normal Contact Force: A force that acts at right-angles to a surface as a reaction to a force on that surface.
Non-Contact Forces: Forces that can be exerted between objects without them being in contact with one
another. There are 3 main non-contact forces you need to know about:
1. Gravity - A force occurring between 2 objects that have mass. It is always attractive.
2. Magnetism – A force acting between magnetic poles. It can attract and repel.
3. Electrostatic charges – These charges exert forces on each other at a distance. They attract & repel.
Action-Reaction Forces: Pairs of forces acting on different objects in opposite directions.
, Circuit Symbols
Series & Parallel Circuits
Series Circuits:
o This circuit contains just 1 loop, around which an electric current can flow.
o Components cannot be switched on/off individually.
Parallel Circuits:
o This circuit contains more than 1 loop.
o Components can be switched on/off individually.
o Current size leaving the cell equals the sum of the currents in each of the
branches.
Physics Basics
Work, Energy, & Power
Energy: Something that is needed to make things happen or to change something.
Work Done: A measure of the energy transferred when a force acts through a distance.
o Work done is measured in Joules.
o 𝑾𝒐𝒓𝒌 𝒅𝒐𝒏𝒆 (𝑱) = 𝑭𝒐𝒓𝒄𝒆 (𝑵) 𝑿 𝑫𝒊𝒔𝒕𝒂𝒏𝒄𝒆 𝒎𝒐𝒗𝒆𝒅 𝒊𝒏 𝒕𝒉𝒆 𝒅𝒊𝒓𝒆𝒄𝒕𝒊𝒐𝒏 𝒐𝒇 𝒕𝒉𝒆 𝒇𝒐𝒓𝒄𝒆 (𝑴)
o You can measure that work done by recording the size of the force and the distance moved in the
direction of the force. Having recorded these values, multiply them together to find the value for the
work done.
Power: The rate at which energy is transferred [the rate of doing work].
o When energy is being transferred by forces, then power is also the rate of doing work.
o Power is measured in Watts => 1 Watt = 1 Joule/1 second.
1 horsepower = 746 Watts.
𝑾𝒐𝒓𝒌 𝒅𝒐𝒏𝒆 (𝑱) 𝑬𝒏𝒆𝒓𝒈𝒚 (𝑱)
o 𝑷𝒐𝒘𝒆𝒓 (𝑾) = OR 𝑷𝒐𝒘𝒆𝒓 (𝑾) =
𝑻𝒊𝒎𝒆 𝒕𝒂𝒌𝒆𝒏 (𝑺) 𝑻𝒊𝒎𝒆 𝒕𝒂𝒌𝒆𝒏 (𝑺)
Changing the energy of a system:
1. Work done through forces: A body can be lifted through a vertical height by a force. This will
increase the store of GPE.
2. Electrical equipment: A cell in a circuit provides a potential difference so that components in the
circuit can transfer energy into other forms, such as TE.
3. Heating a material: Supplying TE to a system will increase the KE of the particles in the material. Its
temperature will increase if it is not changing state.
Interacting Forces
Pairs of forces can interact at a distance or by direct contact.
Contact Forces: The forces between objects that are touching.
In each case there is an interaction pair of forces that act in opposite directions.
The forces can be represented by vectors.
Tension, drag, and friction are all contact forces.
Normal Contact Force: A force that acts at right-angles to a surface as a reaction to a force on that surface.
Non-Contact Forces: Forces that can be exerted between objects without them being in contact with one
another. There are 3 main non-contact forces you need to know about:
1. Gravity - A force occurring between 2 objects that have mass. It is always attractive.
2. Magnetism – A force acting between magnetic poles. It can attract and repel.
3. Electrostatic charges – These charges exert forces on each other at a distance. They attract & repel.
Action-Reaction Forces: Pairs of forces acting on different objects in opposite directions.
, Circuit Symbols
Series & Parallel Circuits
Series Circuits:
o This circuit contains just 1 loop, around which an electric current can flow.
o Components cannot be switched on/off individually.
Parallel Circuits:
o This circuit contains more than 1 loop.
o Components can be switched on/off individually.
o Current size leaving the cell equals the sum of the currents in each of the
branches.
