Cheatography
https://cheatography.com
A cheat sheet explaining the basic rules of physics, including standard units, an overview of units, and important formulas to know
This is a draft cheat sheet. It is a work in progress and is not finished yet.
Introduction to Physics
There are 3 ways to read in physics: reading to know, reading to discover, and reading to understand. |
Key Words
Often we are given information from the wording of the problem that is not directly stated. For example, if a problem tells us that an object started from rest, we know that the initial velocity is zero, even though the problem didn't say anything about velocity. |
If a problem says... |
It is really telling us about... |
Beginning |
Starting/Initial Velocity |
From ... to ... |
Starting at ... and stopping at ... |
From rest |
Initial velocity (VI) |
Reaches |
Final (velocity, sometimes) |
Freely falling |
Gravity |
Scalar vs. Vector
A scalar is a quantity that has a magnitude only. A vector is a quantity with a magnitude and a direction. |
Scalar |
Vector |
8 years old |
10 kilometers east |
14 days |
12 miles west |
3 meters |
2 inches south |
8 apples |
5 yards north |
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Conversion Tables
1 kilometer |
1000 meters |
1 centimeter |
0.01 meter |
1 gram |
0.001 kilogram |
Standard Units in Physics
There are specific units that you must use when solving physics problems. If your final answer uses units other than these, it will be marked wrong. |
Measurement |
Unit |
Abbr. |
Distance |
meters |
m |
Displacement |
meters |
m |
Velocity |
meters/second |
m/s |
Acceleration |
meters/second2 |
m/s2 |
Force* |
newtons |
N |
Weight |
newtons |
N |
Mass |
kilograms |
kg |
Time |
seconds |
s |
Work |
joules |
J |
Gravity** |
meters/second2 |
9.8 m/s2 |
*: see force box below for everything measured in newtons.
*: Gravity will always be 9.8 m/s2 unless a problem specifically mentions a zero-gravity environment (rare but possible).
Types of Force
There are several types of forces that are all measured in newtons. It is important to remember that every force is equal to mass times acceleration, but certain forces have easier ways of measuring them. |
FG |
Force of gravity |
Mass × gravity |
FD |
Driving force |
FG sin θ |
FF |
Force of friction |
μ × FN |
FN |
Normal force |
FG cos θ |
The website I made this cheat sheet on doesn't have a subscript option (the little letters used for things like initial velocity) so I put it in superscript instead. However, you will see it in subscript on the test, so be aware.
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Formula List
Every formula you'll need for the class should be here! |
Area of a rectangle |
length × width |
Area of a triangle |
½ length × width |
Area of a trapezoid |
½ (b1 + b2) × height |
Distance |
speed × time |
Speed |
distance / time |
Weight (FG) |
mass × gravity |
Force (general) |
mass × acceleration |
FD |
FG × sin θ |
FN |
FG × cos θ |
FF |
μ × FN |
Work |
Force × displacement |
Kinetic energy |
½ mass × velocity2 |
Potential energy |
mass × gravity × height |
Centimeters to meters |
cm × 0.01 |
Kilometers to meters |
km × 1000 |
Acceleration |
VF - VI / TF - TI |
Kinematic Formulas
Δx = VF2 - VI2 / 2a |
No t |
VF = VI + at |
No Δx |
Δx = VIt + ½at2 |
No VF |
Δx = (VF + VI / 2) × t |
No a |
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