....describes the movement of the object.
Velocity-is an objects speed in a stated direction. This is called the vector quantity. The direction of velocity is indicated by a - or + sign. If a car was travelling +40mph and another is travelling -40mph they are simply traveling in oppisite directions.
Displacement is used to describe the distance covered in a certain direction. It is another vector quanity.
The accelertaion of an object is the rate at which its velocit changes. It is a measure of how quickly an object is speeding up or how slowly an object is slowing down.It is measure in m/s(2)
The slope of a velocity time graph represents the acceleration of an object- (the steeper the gradient the greater the acceleration). The area underneath the line represents the total distance travelled.
Forces- are pushes or pulls. eg friction, weight and air resistance. Forces may be different sizes and act in different directions. It is measured in NEWTONS (N)
Stationary objects- have equal forces acting upon them
Action force- When object A pushes of pulls object B
Reaction force-When object B pushes or pulls object A
How forces affect movement...
Resultant force- is the balance of forces acting upon something.
Accelerating- When the driving force is greater that the resistive force.
Braking-When the resistive force is greater than the driving force
Moving at a constant speed-When the driving an resitive force are equal
If an unbalanced force acts on an object then the acceleration of the object will depend on...
- the size of the unbalanced force-the bigger the force, the greater the acceleration
- the mass of the object-the bigger the mass, the smaller the acceleration.
the constant velocity reached by a falling body (gravitational force is equal to the frictional forces acting upon it).
Falling objects experience two forces...
- the downward force of weight which always stays the same
- the upward force of resistance or drag
depend on the thinking distance and the braking distance.
Stopping Distance cont...
Factors affecting stopping distances..
The speed of the vehicle
The mass of tehe vehicle
The conditions of the vehicle and road
The drivers reaction time
Momentum- is the measure of the state of movement of an object. It is dependant on two things;
The mass of the object
The Velocity of the object
cars have a lot of safety features to try and minimise injury and reduce the number of deaths;
- crumple zones- absorb momentum
- power assisted steering and anti-lock brake systmes- help the driver control direction
- cushioing during impact
- seatbelts which lock when the car brakes
imposed risk - eg coal mining, operating machinery
voluntary- smoking, rock climbing
Displacement- a disnce covered in a certain direction
Magnitude- a measure of size
Vector- a quanity that has both size and direction