Module 3 Flashcards
Scalar Quantity
A quantity with magnitude but not direction.
Vector Quantity
A quantity with magnitude and direction.
Speed
Rate of change of distance travelled.
Average Speed
Total distance travelled divided by the time taken.
Instantaneous Speed
Total distance travelled divided by the time taken.
Displacement
Distance moved in a stated direction.
Velocity
Rate of change of displacement.
Acceleration
Rate of change of velocity.
Thinking Distance
Distance travelled between the driver observing the hazard and pressing the brake
Braking Distance
Distance travelled from when the driver starts braking to when the car stops.
Stopping Distance
Distance travelled from when the driver sees a problem to when the car stops. (thinking distance + braking distance)
Newton
One newton is the force that causes a mass of 1kg to have an acceleration of 1ms^-2.
Weight
The weight of an object is the gravitational force acting on the object.
Drag
The resistive force experienced by an object moving through a fluid.
Terminal Velocity
The constant speed reached by an object when the drag force (and upthrust) is equal and opposite to the weight of the object. (At terminal velocity, drag + upthrust = weight)
Moment of a Force
The force multiplied by the perpendicular distance from a specified point (pivot).
Pinciple of Moments
If an object is balanced, then the sum of the clockwise moments about a pivot is equal to the sum of the anticlockwise moments about the same pivot.
Equilbrium
For an object to be in equilibrium, the resultant force = 0N and the resultant moment = 0Nm.
Couple
A couple is a pair of equal and parallel but opposite forces, which tends to produce rotation only.
Torque of a Couple
The force multiplied by the perpendicular distance between the forces.
Centre of Gravity
A point where the entire weight of an object appears to act.
Density
Mass per unit volume.
Pressure
Normal force exerted per unit cross-sectional area.
Upthrust
The upward buoyant force exerted on a body immersed in a fluid.
Archimedes’ Principle
The upthrust on an object immersed in a fluid is equal to the weight of fluid it displaces.
Work Done
The force multiplied by the distance moved in the direction of the force.
Joule
The work done by a force of one newton acting over a distance of one metre.
Conservation of Energy
Energy cannot be created or destroyed; it can only be transformed into other forms.
Kinetic Energy
The energy of a body due to the motion of the body.
Potential Energy
The stored energy associated with a force due to the position of a body.
Gravitional Potential Energy
The energy stored in a mass due to its position in a gravitational field.
Power
Rate of work done.
Watt
One joule per second.
Hookes’ Law
The tensile force applied is directly proportional to the extension (or compression) of the spring, provided that the limit of proportionality is not exceeded.
Force Constant
Tensile force per unit extension.
Tensile Stress
Tensile force per unit cross-sectional area of a material.
Tensile Strain
Extension per unit length of a material.
The Young Modulus
Tensile stress per unit tensile strain.
Ultimate Tensile Strength
The maximum stress a material can withstand.
Elastic Deformation
The material will return to its original length/shape once the tensile force has been removed. It will not be permanently deformed.
Plastic Deformation
The material will not return to its original length/shape once the tensile force has been removed. It will be permanently deformed.
Elastic Potential Energy
The energy stored in an object due to its deformation.
Newton’s First Law
A body will remain at rest or continue to move with constant velocity unless acted upon by a resultant external force.
Newton’s Second Law
The resultant force acting on an object is proportional to the rate of change of momentum and the change in momentum occurs in the same direction as the resultant force.
Newton’s Third Law
When body A exerts a force on body B, body B exerts a force on body A which is equal in magnitude but opposite in direction.
Linear Momentum
Mass x Velocity
Impulse
Force x time for which the force acts.
Conservation of Momentum
The total momentum of a closed system is constant, provided that no external forces are applied.
Perfectly Elastic Collision
During the collision, no kinetic energy is transferred into other forms. Kinetic energy is conserved.
Inelastic Collison
During the collision, some kinetic energy is transferred into other forms.
