Forces And Motion (P1, P2, P3) Flashcards
Define displacement
- Vector quantity
* The direction and distance that an object moves in a straight line from start to finish.
Define speed
- Scaler quantity
* Just how fast an object is moving (no direction).
Define velocity
- Vector quantity
* How fast an object is moving in a certain direction.
What is the speed equation?
Speed = Distance / Time
What is the equation for acceleration?
Acceleration = (Final Velocity - Initial Velocity) / Time
OR
Acceleration = Change in Velocity / Time
What is the first law of motion?
Balanced forces mean no change in velocity.
What is the second law of motion?
A resultant force means acceleration or deceleration.
What is the third law of motion?
If an object exerts force onto another object, then that object exerts and equal and opposite force back.
What is the force equation?
Force = Mass x Acceleration
Define distance
- Scalar quantity
* How far an object moves (no direction)
What does gradient measure in DT and VT graphs?
Distance-Time -> Speed
Velocity-Time -> Acceleration
What does the area under the graph represent in DT and VT graphs?
Distance-Time -> Nothing
Velocity-Time -> Distance
What is the difference between vector and scalar quantities?
Vector -> Have magnitude and direction
Scalar -> Have only magnitude
Give some examples of scalar quantities.
Time, Speed, Distance, Mass
Give some examples of vector quantities.
Acceleration, Force, Momentum, Weight, GFS
What is a resultant force?
A single force that has the same effects as all the forces acting on an object.
What happens when the resultant force is zero?
The object remains stationary or travels at a constant velocity.
What happens when the resultant force is not zero?
The velocity of the object changes.
How does the parallelogram method work?
- Pick a scale for the forces (e.g. 1N = 2cm)
- Draw the two forces at the appropriate angle to each other at the correct length according to the scale (e.g. 20N = 10cm)
- Complete the parallelogram with the other two lines
- Measure the centre line
- Convert this to a force using the scale (e.g. 25cm = 12.5N)
What two factors increase the FORCE required to stop a car (braking force)?
- Speed of the car
* Mass of the car
What is the stopping difference, thinking distance and braking distance?
- Stopping distance -> Total distance required for a car to safely stop -> Stopping distance = Thinking distance + Braking distance
- Thinking distance -> Distance travelled by the car while the driver is reacting
- Braking distance -> Distance travelled by the car while the braking force acts
What factors affect thinking distance?
- Drugs, Tiredness, Alcohol
- Speed
- Distractions
What factors affect braking distance?
- Speed
- Car conditions / brakes
- Road conditions
