PHYSICS DEFINITIONS
Vector
- A physical quantity which has both magnitude (size) and direction.
- eg . acceleration, velocity (instantaneous velocity & average velocity), displacement,
forces
Scalar
- A physical quantity with magnitude (size) only.
- eg. speed, distance, time, mass, work
Resultant vector
- The single vector which has the same effect as the original vectors acting together.
Distance
- The length of the path travelled.
Displacement
- A change in position.
Speed
- The rate of change of distance.
Velocity
- The rate of change of displacement.
Acceleration
- The rate of change of velocity.
Weight
- The gravitational force the Earth exerts on any object on or near its surface.
- Fg
Normal force
- The perpendicular force exerted by a surface on an object in contact with it.
- FN
Frictional force
- The force that opposes the motion of an object.
- Due to a surface.
- Acts parallel to the surface which the object is in contact.
- Ff
, Static friction
- Friction between two solid objects that are not moving relative to each other.
- It can prevent an object from sliding down an inclined plane.
- Maximum static friction = just before the object begins to move.
Kinetic friction
- Occurs when two objects slide across each other and rub together.
Force diagram
- Picture of the objects showing all the forces acting on the object using labelled arrows.
Free body diagram
- Shows all the forces acting on a single isolated body.
Coefficient of friction
- The ratio of the frictional force between the object on the surface to the normal force
acting on the object.
- No units, ratio.
Newton's first law
- An object will continue in a state of motion or at uniform (moving with constant) velocity
unless it is acted upon by a net or resultant force.
Inertia
- The property of an object that causes it to resist a change in its state of rest or uniform
motion.
Newton's second law
- When a net force (Fnet) is applied to an object of mass, m, it accelerates in the direction
of the net force.
- The acceleration, a , is directly proportional to the net force and inversely proportional to
the mass.
Newton's third law
- When object A exerts a force on object B, object B simultaneously exerts an oppositely
directed force of equal magnitude on object A
Linear momentum
- The product of the mass and velocity of an object
- Vector
- The same direction as the velocity vector
Newton's second law in terms of momentum
- The net force acting on an object is equal to the rate of change of momentum
Vector
- A physical quantity which has both magnitude (size) and direction.
- eg . acceleration, velocity (instantaneous velocity & average velocity), displacement,
forces
Scalar
- A physical quantity with magnitude (size) only.
- eg. speed, distance, time, mass, work
Resultant vector
- The single vector which has the same effect as the original vectors acting together.
Distance
- The length of the path travelled.
Displacement
- A change in position.
Speed
- The rate of change of distance.
Velocity
- The rate of change of displacement.
Acceleration
- The rate of change of velocity.
Weight
- The gravitational force the Earth exerts on any object on or near its surface.
- Fg
Normal force
- The perpendicular force exerted by a surface on an object in contact with it.
- FN
Frictional force
- The force that opposes the motion of an object.
- Due to a surface.
- Acts parallel to the surface which the object is in contact.
- Ff
, Static friction
- Friction between two solid objects that are not moving relative to each other.
- It can prevent an object from sliding down an inclined plane.
- Maximum static friction = just before the object begins to move.
Kinetic friction
- Occurs when two objects slide across each other and rub together.
Force diagram
- Picture of the objects showing all the forces acting on the object using labelled arrows.
Free body diagram
- Shows all the forces acting on a single isolated body.
Coefficient of friction
- The ratio of the frictional force between the object on the surface to the normal force
acting on the object.
- No units, ratio.
Newton's first law
- An object will continue in a state of motion or at uniform (moving with constant) velocity
unless it is acted upon by a net or resultant force.
Inertia
- The property of an object that causes it to resist a change in its state of rest or uniform
motion.
Newton's second law
- When a net force (Fnet) is applied to an object of mass, m, it accelerates in the direction
of the net force.
- The acceleration, a , is directly proportional to the net force and inversely proportional to
the mass.
Newton's third law
- When object A exerts a force on object B, object B simultaneously exerts an oppositely
directed force of equal magnitude on object A
Linear momentum
- The product of the mass and velocity of an object
- Vector
- The same direction as the velocity vector
Newton's second law in terms of momentum
- The net force acting on an object is equal to the rate of change of momentum
