# physics 2

notes on P2

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• Created by: Anam
• Created on: 31-03-11 20:10

## time graphs

Distance-Time Graphs

a straight diagnal line shows constant speed

a horizontal line shows the stop

a positive correlation curve shows acceleration

the slope can be used to work out the speed

Velocity-Time Graphs

a straight line shows constant acceleration

a horizontal line shows stead speed

a positive corellation curve shows increasing acceleration

the slope can be sued to work out acceleration

For both graphs

use this equation to work out speed or acelleration :

vertical value / horizontal value

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## Speed

How do we make things speed up or slow down ?

When two objects interact, the forces they exert on eachother are equal and opposite.

The overall unblanced force is called the resultant force.

If the object isnt moving, its resultant force is zero and the force's effect on the object makes it stay at rest

If the object is moving and its resultant force is zero, the force's effect on the object is constant velocity.

If the object is moving with a non-zero resultant force in the same direction as the motion of the object, the force's effect on the object is  accelerating

If the object moving with a non-zero resultant force in the opposite direction of the motion of the object, the force's effect on the object is deccelerating

If the resultant force is zero -

the object stays stationary if it wasnt moving

keeps on moving at the constant speed if it was moving

resultant force = mass x acceleration

(N)                        (kg)      (m/s squared)

When a vehicle travels at a steady speed, the friction force and the drving force are balance .

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