PHYSICS SECTION 1

A scalar quantity is a physical quantity that only has a magnitude (size)

• speed
• mass

A vector quantity is a quantity with a magnitude (size) and a direction.

• velocity
• force

SPEED=Distance/Time

1.4m/s

5.5m/s

13m/s

31m/s

Acceleration= change in velocity/ time

This is just negative acceleration, for example, slowing down in a car 

This is the constant acceleration

v^2 - u^2 = 2 x A x X

gradient= speed

flat sections= object is stationary 

Steeper graph= going faster

curves= acceleration

steep curve= speeding up

leveing off curve = stopping (deceleration)

Gradient= acceleration

flat sections=  steady speed

steeper the gradient= greater the acceleration or deceleration ( velocity time graphs can have either a positive or negative gradient)

uphill sections (/) = acceleration#

Downhill sections (\)= deceleration

PS IF THE GRAPH IS CURVED, DRAW A TANGENT!

The distance traveled is the area under the graph.

if the resultant force on a stationary object is zero, the object will stay stationary. if the resultant force on a moving object is zero, the object will carry on moving at the same velocity

Force = mass x acceleration

OR

F = M x a

It can cause serious injury because a large deceleration needs a large force (f=mxa)

the force can be reduced by slowing the object down over a longer time, respectively decreasing the deceleration.

Weight = Mass x Gravity

Centripetal Force occurs when an object is moving in a circle. If an object is traveling in a circle at a constant speed, it is constantly changing direction, so it is constantly changing velocity. this means the object is accelerating. it also means there must be a resultant force present and in this case, that force is called tension, which acts towards the centre of the circle.

• use a trolley and ramp

APPARATUS: trolley, ramp, light gates connected to data loggers, string, hanging mass

Method

• measure the mass of the trolley and the mass hanging from the hanging hook.
• adjust the height of the ramp until the trolley starts to move 

This means that other forces are applied (like the force of gravity caused by the hanging mass attached to the trolley) will be the main cause of the trolley accelerating as it travels down the ramp

• Mark a line just before the first light gate so you make sure the trolley travels the same distance every time
• attach the trolley to a hanging mass using a string then let go so the trolley starts to move
• the light gates will capture the speed of the trolley 
• the acceleration can be found using Acceleration= change in velocity/time

This is the tendency for motion to remain unchanged.

until acted on by a resultant force, an object will remain at rest.

(Newton's 1st law) 

this tendency is known as Inertia and it measures how difficult it is to change the velocity of an object

inertial mass can be found using m=f/a

when two objects interact the forces they exert on each other are equal and opposite. 

Momentum = mass x velocity

If an object has a large mass, the greater the velocity and thus means it has a greater momentum

Force = change in momentum/time

this is because forces cause a change in momentum

Stopping distance = thinking distance + braking distance 

they have a squared relationship

speed x 2  = distance x4

speed x3 = distance x9

0.5 x mass x speed^2 = F x d

0.5 x mass x speed^2

useful energy out/ total energy in