Definitions Flashcards
Vector
A physical quantity that has both magnitude and direction
Eg velocity, force, acceleration, electric current
Scalar
A physical property with a magnitude but not a direction
Eg speed, distance, pressure, potential difference
Displacement
The distance travelled in a particular direction, measured in metres. It is a vector quantity
Instantaneous speed
The speed of an object at a given moment in time
Velocity
The displacement per unit time, measured in metres per second. It is a vector quantity
Acceleration
The rate of change of velocity, measured in metres per second squared. It is a vector quantity
Newton
Unit of force. 1 Newton is the force which gives a mass of 1kg an acceleration of 1ms^-2
What are the 4 factors that affect the magnitude of the drag force?
Velocity, cross-sectional area, roughness of surface, shape
Terminal velocity
The velocity at which an object’s drag equals it’s accelerating force. Therefore there is no resultant force and zero acceleration
Centre of gravity of an object
Is a point where the entire weight of an object appears to act
Couple
A pair of forces that tends to produce rotation only
Torque
The turning effect due to a couple, measured in Newton metres
Moment of force
The turning effect due to a single force, calculate from: force x perpendicular distance from a given point, measured in Newton metres
Thinking distance
The distance travelled from seeing the need to stop to applying the breaks
Braking distance
The distance a vehicle travels while decelerating to a stop
