Updated on 15/2/2019
Patapee Lohprasert ()
Mechanical Engineering Department, Imperial College London
, Contents
1 Physical quantities and units ................................................................................................................. 1
2 Measurement techniques ....................................................................................................................... 1
3 Kinematics .................................................................................................................................................... 1
4 Dynamics ...................................................................................................................................................... 2
5 Forces, density and pressure ................................................................................................................. 2
6 Work, Energy and Power ........................................................................................................................ 3
9 Deformation of Solid................................................................................................................................ 3
14 Waves ............................................................................................................................................................. 3
16 Superposition .............................................................................................................................................. 4
17 Electric Fields ............................................................................................................................................... 5
19 Current of electricity ................................................................................................................................. 5
20 D.C. circuits................................................................................................................................................... 6
26 Particle and nuclear physics .................................................................................................................. 7
,Key Points and Definitions
[AN] Author’s Notes
** Key Points that are not “definitions” eg. ‘define...’ ‘what is meant by…’
(**The topic numbers below are according to the 2019-2021 Syllabus and the definition and key
points are all from the mark scheme up to June 2018)
https://www.cambridgeinternational.org/Images/329533-2019-2021-syllabus.pdf
1 Physical quantities and units
Scalar Quantity: has magnitude only
Vector Quantity: has magnitude and direction
2 Measurement techniques
Systematic errors: constant error (in all readings) // cannot be eliminated by averaging
// error in measuring instrument
Random errors: readings scattered (equally) about the true value // error due to
observer // can be eliminated by averaging
Precision: smallest scale division of instrument
Accuracy: how close are the readings to the true value
3 Kinematics
Velocity: rate of change in displacement
**Velocity is the gradient of the displacement time graph
Acceleration: rate of change in velocity
**Acceleration is the gradient of the velocity time graph
Difference between distance and displacement: distance is scalar, and displacement is
vector. Displacement is the shortest distance between two points, distance is the sum of
the lengths moved.
**Displacement is the area under graph of velocity time graph
[AN] You should also know the all the SUVAT equations for this part (Remember all of them,
don’t waste time to derive them).
, 4 Dynamics
Newton’s first law: a body remains at rest or at constant velocity unless acted on by a
resultant external force
Newton’s second law: Force =rate of change in momentum (Also the definition of force)
𝑚𝑣−𝑚𝑢 𝑣−𝑢
**𝐹 = = 𝑚( ) = 𝑚𝑎 !! (F = ma)
𝑡 𝑡
Newton’s third law: for every action, there is an equal and opposite reaction
Weight: weight is the force due to the gravitational field // force due to gravity or
gravitational force
**𝑊 = 𝑚𝑔
Principle of conservation of momentum: Total momentum before the collision is equal
to the total momentum after the collision when there is no resultant external force acting
/ in an isolated system
**Although momentum is always conserved, Kinetic energy my change to other form
of energy, hence energy lost from the system
Elastic collision: Total kinetic energy before collision is equal to the total kinetic energy
after the collision // relative speed of approach = relative speed of separation
5 Forces, density and pressure
Centre of gravity: the point where all the weight of the body is considered to act
Center of mass: the point on an object where all its mass is considered to act
Principle of moments: the sum of the clockwise moments about a point is equal to the
sum of anticlockwise moments about the same point
Moment of a force: product of force and the perpendicular distance from a pivot
Torque of a couple: one of the forces times by the perpendicular distance between the
forces.
Equilibrium: no resultant force and moment (torque)
Density: mass / volume
Mass: Quantity of matter in a body // property in a body resisting changes in motion
Pressure: Force per unit area (normal to the force)