Module 1 definitions Flashcards
Define a vector quantity
Has both magnitude and direction
Define a scalar quantity
Only contains magnitude and no direction
Define velocity
The rate of change of displacement
Define displacement
The distance travelled in a particular direction
Define instantaneous speed
The speed of an object at a given point in time.
Define acceleration
The rate of change of velocity of an object
Define stopping distance
The total distance travelled from when the driver first sees a reason to stop, to when the vehicle stops.
Define thinking distance
The distance travelled by the vehicle from when the driver sees a problem and then brakes are applied.
Braking distance
The distance travelled by a vehicle after applying the brakes.
Define mass
The amount of matter
Weight
The gravitational force on an object
Centre of mass
An imaginary point where the entire weight of an object appears to act.
Centre of gravity
A point where the weight appears to act.
Drag
A frictional force that opposes the motion of the object
Terminal velocity
The constant speed reached by an object when the drag force is equal and opposite the weight of the object
Moment
The product of force and the perpendicular distance from a pivot.
Principle of moment
For a body in rotational equilibrium, the sum of anticlockwise moments about any pivot is equal to the sum of the clockwise moments about the same point.
Torque
The product of one of the forces and the perpendicular separation between the forces
Density
Mass per unit volume
Fluid
Any substance that can flow
Archimedes principle
The upthrust exerted in a body immersed in a fluid, whether full or partially submerged is equal to the weight of the fluid that the body displaces.
Work done
The product of force and the distance moved in the direction of the force.
Kinetic energy
Energy associated to the movement of an object
Gravitational potential energy
The energy due to the position of an object in the Earth’s gravitational field.
Principle of conservation of energy
Energy cannot be created or destroyed only transferred from one form to another.
Power
Rate of work done
Extension
The increase in length of an object when a tensile force is exerted on it
Tensile force
Equal and opposite forces acting on a material to stretch it
Tensile deformation
A change in shape of a object due to tensile forces
Compressive deformation
A change in the shape of an object dude to the compressive forces
Hooke’s law
The force applied is directly proportional to the extension of the spring unless the limit of proportionality is exceeded.
Plastic deformation
An irreversible change in the shape of an object due to a tensile force. The removal of the force produces a permanent deformation.
Elastic deformation
A reversible change in the shape of an object due to a tensile force. The removal of the force will return the object back to its original shape and size.
Elastic potential energy
The energy stored in a object due to its deformation
Tensile stress
The force per unit cross sectional area.
Tensile Strain
The extension per unit length
Limit of proportionality
The value of force beyond which stress is no longer proportional to strain.
Ultimate tensile strength
The maximum stress that material can withstand before it breakss
Young modulus
The ratio of tensile stress to tensile strain when the quantities are directly proportional to each other.
Newtons first law
A body will remain at rest or continue to move with constant velocity unless acted upon by a resultant force
Newtons second law
The rate of change of momentum of an object is directly proportional to the resultant force and it takes place is the direction of the force.
Newtons third law
When two object interact, each exert equal but opposite forces on the other during the interaction.
Momentum
The product of mass and the velocity of the mass
Conservation of momentum
For a system of interacting objects the total momentum in an specific direction remains constant as long as no external forces act on the system
Inelastic collision
A collision in which kinetic energy is transferred in other forms eg heat
Elastic collisions
Momentum and kinetic energy are conserved
Impulse
The product of a force and the time for which the force acts
Couple
A pair of parallel forces pointing in the opposite direction
Newton
When 1kg of mass has an acceleration of 1ms-2.
Free fall
The motion of an object accelerating under gravity with no other force acting on it.
Efficiency
The ratio of useful output energy to total input energy.
Elastic limit
The value for stress or force beyond which elastic deformation becomes plastic deformation and the material will no longer return to its original shape and size when the stress or force is removed.
Yield points
Tension
The pulling force exerted by a string, cable or chain on an object.
Normal contact force
The force exerted by a surface on an object, which acts perpendicularly to the surface.
Upthrust
The upward buoyant force exerted on a body immersed in a fluid.
Friction
