Physics AS Mechanics Unit 2

Force x perpendicular distance

...A physical quantity with both magnitude and direction

...A physical quantity with magnitude only

Change in distance / Change in time

Change in velocity / Change in time

v = u + at

2s = (u+v) x t

v^2 = u^2 + 2as

s = ut + 0.5 x a x t^2

Mass x Acceleration

Force x distance moved

0.5 x m x v^2

m x g x (change in h)

0.5 x k x e^2

mgh - 0.5 x m x v^2

The rate of transfer of energy

Measured in Watts. 

Energy transferred / time

Work done / time

Force x Velocity 

useful energy transferred by the machine / total energy supplied into the machine

Energy cannot be destroyed or created, it can only be turned into different forms.

Energy is measured in Joules.

One Joule is defined as the energy required to move an object of weight 1N through a distance of 1m. 

Power is measured in Watts.

One Watt is defined as a rate of transfer of energy equal to 1 Joule per second. 

Horizontal = F cos theta

Vertical = F sin theta 

Sum of Clockwise moments = Sum of Anti-clockwise moments

Speed x time

Area under the line of a speed-time graph

Horizontal component = initial speed x time

Vertical Component = 0.5 x gravity x time^2 

First Law

Objects either stay at rest or remain in uniform motion in the same direction unless acted on by an external force

Second Law 

Force = mass x acceleration

Third Law (Law of Inertia)

Weight = mass x gravity 

The distance travelled in the time it takes the driver to react to the hazard.

Speed x reaction time 

The distance it takes for the car to stop completely once the driver has reacted.

v^2 / 2a 

Thinking distance + Braking Distance

• Greasy/icy road
• Medication/Drugs
• Alcohol
• Road conditions
• Weather
• Tyre conditions 

• Vehicle Bumpers
• Airbags
• Collapsible Steering Wheel
• Crumple zones
• Seat Belts

They all increase impact time, which reduces impact force, which lessens the force of the crash on the driver.