Forces and Motion Classroom

Taught by [Shadowsoul]
  
This classroom mainly deals with Forces and Motion but if you have questions at a year 11 level, I'm willing to answer them for you or research them for you. Ask anything of me, if I don't know it I can ask my teacher or another teacher here at the academy.

Students

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Questions

Q:

Physics equations

Class notes

(these notes are the ones i get from my teacher at school. Mrs Ambroselli)

SI units are the units used internationally to measure physical quantities. They are often called the metric system

Derived units- Quantities from the basic quantities

Scientific notation
-Used for very very big & small numbers
-Written as factors of 10
-Numbers written in scientific notation re made up of 4 parts
-The mantissa is always above one but below 10
-if the power is negative (-ve) - a small number
-if the power is positive (+ve) - a big number

Significant digits
-used for accuracy
-Non zero digits are always significant (1,2,3.....etc)
-All final zero after the deicmal point are significant eg. 56.0 has 3 significant digits

Operations using significant digits
-Sum or difference of two values is as precise as the least precise values

Percentage uncertainty = Absolute uncertainty/observed measurement x 100%

Uncertainty calculations
for +/- add absolute uncertainty
for x\ / add % uncertainty

Error
-Error is a measure of innaccuracy
-closeness to the acepted value
Absolute Error (Ea) = 1 observed value - accepted value
Relative Error (Er) = Ea/accepted error x 100

Acceleration

A = Vf - Vi / Tf - Ti
Where A=acceleration in ms-1 or m/s2 or m/s/s
Vf = final velocity in m/s
Vi = Initial (starting) velocity in m/s
Tf = Final time in seconds
Ti = Initial time in seconds

A= v/t
(Acceleration = velocity/time)

+ve A is accelration
-ve A is decceleration

Vf = Vi+at

Displacement using Uniform Acceleration
-Average velocity of a uniformly accelerating object is the middle velocity

velocity Time graphs
-Straight line sloping upwards indicates constant acceleration
-Straight line sloping down indicates deceleration or negative acceleration
-A horizontal line indicates zero acceleration ie constant velocity
-Displacement can be calculated by finding the area under the line
The gradient of the line gives acceleration

Equations of Motion
1. motion with (uniform) velocity

v=constant
v=s/t
or
s=vt

2. Motion with uniform acceleration
a) A=constant
b) V=v+u/t
c) V=u+at
d) s= ut+1/2at^2
e) v= u^2+2as
f) s= (u+v)t/2

Acceleration due to gravity
-Objects in a vaccum fall at the same rate regardless of their rate
-Motion due can take two forms: vertical and projectile
-galleo proved that: two objects of different masses dropped form the same hieght at the same time should strike the ground simeontaneously

Types of freefall motion:
1. Objects being dropped or thrown down
2. Object is being thrown upwards
* upward motion is true

A gravity = -10ms^-2
Gravity= 9.8m/s
-This means an object will increase it's velocity by 10m/s in every second




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