Basic Physics Notes

Physics Notes

Kinematics

Distance in the total distance travelled (Scaler)

Displacement it the change in position from the starting point (vector)

To add vectors, add those head to tail, remember to calculate the direction as well as magnitude

Graphs

Displacement-time graphs ---- Gradient is the average speed

Velocity time graphs----- Area is the change in displacement gradient = acceleration

Equations

Where;

V is final velocity

U is initial velocity

T is time

A is acceleration

S is displacement

Relative Velocities

Set up equations with subscript referring to each of their context E.G.

V¬PA=VPB + VBA

e.g. the velocity of P relative to frame A is the velocity of P relative to frame B and the velocity of frame B to A

Keep in mind that V¬PA= -VAP

Dynamics

Newtons laws

1- Inertia- An object with remain at rest or continue to move in a straight line at a constant speed unless an unbalanced force acts

2- An accelerating object, this is proportional to the unbalanced forces acting and the mass such that

F=MA Force =mass x acceleration

3- For every action force there is an equal and opposite reaction.

Impulse and momentum

MV is and objects momentum or P

F∆T= ∆P=I Impulse

Measured in kgms-1 or Ns

To get here

F=MA

F=(MV-MU)/ ∆t

F= (Pf - Pi)/∆t

F=∆P/∆T Force is the rate of change of momentum

F∆T= ∆P=I

Impulse = ∆P

= PF - Pi

= Mv-Mu

=F x ∆T

The more momentum an object has the harder it is to stop, a large force is required (over time) to stop an object with a lot of momentum

Conservation of momentum

In an isolated system the total initial momentum equals the total final momentum

The world communicates

Definitions:

Amplitude (A): The maximum distance from the middle position that the particles vibrate

Wavelength : the distance between successive parts of the wave that are in phase

Frequency