Cheatography

# Mechanics Cheat Sheet by liviabrookes

NCEA level 1 mechanics summary sheet with definitions, example questions, etc.

### Speed, Distance, Time

 Speed measured in metres per second, ms-1 Distance measured in metres, m Time measured in seconds, s, a measure of how long something takes D=VxT distance = velocity x time Distance Time Graphs -line upward­s=g­etting farther away -line downwa­rds­=ge­tting closer -flat line=s­taying still

### Force

 force = mass x accele­ration Fnet=ma -weight is a force measured in Newtons which changes depending on where you are eg. Earth vs. Mars -mass is the amount of matter contained in an object measured in kilograms. Effect of doubling the mass or force -if you double the mass but keep the force the same, accele­ration will be halved -if you double the force, accele­ration will be doubled

### Work

 the measure of energy transfer when an object is moved over a distance W=Fd Work (J) = Force (N) x Distance (m) When work is done to an object, the object gains energy When an object does work, it loses energy work done=e­nergy lost or gained The Ramp Question If one ball is thrown up a ramp and the other is dragged up, both balls will gain the same amount of gravit­ational potential energy assuming they are lifted to the same height, so the work done will be equal, assuming no energy is lost as heat and sound.

### Accele­rat­ion­/De­cce­ler­ation

 Accele­ration a measure of how fast your speed is increa­sing, symbol is 'a', measured in ms-2 Decele­ration a measure of how fast your speed is decreasing Speed Time Graphs -line upward­s=c­onstant accele­ration -line downwa­rds­=co­nstant decele­ration -flat line=c­onstant speed -area under the graph=­dis­tance travelled

### Friction and Pressure

 friction is caused when things rub against each other -friction transfers kinetic energy into heat and sound energy -friction increases when rougher or larger surfaces contact -friction ALWAYS opposes motion -it is measured in Newtons, N Air Resistance is a form of friction affecting all objects moving through the air Terminal Velocity occurs when forces become equal and opposite so they are their constant, maximum speed Eg. when a parachute opens the force of air resistance increases because the surface area has increased. This causes the parachuter to decele­rate. pressure is a force spread over an area High Pressure is a force spread over a small area Low Pressure is a force spread over a large area P=F/A where P is measured in Pa, F is N, and A is ㎡.

### Power

 *the speed at which work is done P=W/T where P is measured in W, W is J, T is s eg. if you walk up stairs slowly or quickly the same amount of work has been done. However, doing it faster means you have used more power.
Unrelated to Power
-1/2 the accele­ration means twice the mass
-Accel­eration in freefall has a value equal to the strength of gravity and so is 10ms-2 on Earth
-Weight and gravity force have the same value

### Forces

 -forces can be a push, pull, twist, or turn. -forces are measured in Newtons (N) -when the forces on an object are unbala­nced, that object moves -only commen­t/draw uneven forces unless told otherwise -always have arrows pointing away from the object -always have arrows touching the object the forces are thrust, friction, gravity, and air resistance or support balanced forces mean the object is stationary or travelling at constant speed unbalanced forces mean the object will either speed up, slow down, or change direction

### Energy

 is measured in Joules, J -Kinetic Energy is the energy possessed by a moving object -the more mass the object obtains and the faster it moves, the more kinetic energy it has -Ek=1/2mv^2 -Gravit­ational Potential Energy is the energy stored in an object because it has been raised a certain height above the ground against the force of gravity -Ep=mgh Types of Energy non-stored energy: stored­/po­tential energy: - light and sound -gravi­tat­ional (height) -kinetic (movement) -elastic (spring) -heat -nuclear (atoms) -elect­rical -chemical (batte­ries) Conser­vation of Energy energy is neither created nor destroyed, it is only transf­erred from one state to another when energy is converted from one form to another, a proportion is lost as heat and sound energy due to the force of friction

## Related Cheat Sheets

Science Electricity Review Cheat Sheet
Chemistry Cheat Sheet
Alvl P1: work, energy and power (ch6) Cheat Sheet

## More Cheat Sheets by liviabrookes

Genetics Cheat Sheet
Demand Cheat Sheet
Supply Cheat Sheet