- Created by: Former Member
- Created on: 13-05-13 21:39
Section 1-Froces and motion
MOVEMENT AND POSITION
distance time graphs- gradient indicates speed, straight line-constant speed, horizontal line indicates that the vehicle is stationary, neggative line- changed direction of the car. Velocity time graphs, gradient indicates acceleration, straight line- constant acceleration, horizontal line- constant speed, negative-deceleration.
- Average speed=Distance/Time m/s
- Acceleration=V-U/time m/s2
- The area under a velocity time graph is its area
- Forces are pushes and pulls of one body on another
- Various types of forces include
- Friction- the force that opposed motion
- Air Resistance(Drag)- the friction caused by the object through air - Increases with speed
- Weight- The force due to gravity
- Viscous Drag- the friction between an object through liquids and gases
- Magnetic- The force between a magnet and another magnet (ferrous object)
- Electrostatic- The force between charges, different charges
- Upthrust- Upward force liquids/gases exert on objects
Balanced/Unbalanced Forces- When the upward acting force equals the downward acting force they forces are said to be balanced. When either the upward or the downward force in unequal , the forces are unbalanced and there is a resultant force acting in the direction of the bigger force. Unbalanced forces make an object accelerate/decelerate or change the direction in which theyre moving.
- The extension of a spring is directly proportional to the force acting on it.
- The straight line represents the way the helical spring will return back to itr original shape unless it is pushed beyond its ELASTIC LIMIT, in which case it will not.
- Helical Springs, the force is on the vertical axis/extension on the horizontal, for wires/elastic bands the force is on the horizontal axis. Rubber bands to do not obey hookes law and have a (S) shaped graph.
NEWTONS SECOND LAW- Force=mass*Acceleration meaures in Newtons
Acceleration is directly proportional to force provided the mass is constant. This means a greter force contributes to greater acceleration, bigger masses need more force in order for them to accelerate.
Friction/Braking relating to the law
- The stopping distance is the combined thinking distance plus the braking distance.
- In order to come to rest, the car needs great deceleration, meaning a large force needs to be applied on a low mass. You cannot however conviniently change the mass of the car, and overbraking causes the car to skid.
- Thinking distance is affected by the state of the driver influenced by things like tiredness, alcohol, drugs, weather condition.
- The braking distance is affected by the condition of the road such as icy, wet and the condition of the tire- worn out tire.
ACCELERATION DUE TO GRAVITY
- All objects have the same speed of acceleratio due to gravity without the pressence of air.
- Its is 10m/s2 on Earth and the Weight is usually 10N/kg.
- Weight=mass * Gravitational…