Forces And Motion Flashcards
Acceleration
The rate of change of velocity (ms^-2)
Average Speed
Total distance/Total time of journey (ms^-1)
Braking Distance
The distance travelled between the brakes being applied and the vehicle stopping (m)
Displacement
The direct distance between the start and end point. A vector quantity (m)
Free-fall
When the only force acting upon an object is gravity (g=9.81)
Instantaneous speed
The exact speed of an object at a specific point (ms^-1)
Projectile motion
The motion of an object that is fired from a point with gravity acting upon it. Split into horizontal and vertical components.
Reaction time
The time taken to process a trigger and respond to it
Stopping distance
Thinking distance+ braking distance
Thinking distance
The distance travelled in the time it takes for the driver to react
Velocity
The rate of change of displacement. Vector quantity (ms^-1)
Archimedes’ Principle
The upwards force acting upon an object submerged in a fluid, is equal to the weight of fluid displaced
Centre of gravity
The single point of where the weight of the object is said to act
Centre of mass
The point where the total mass of an object is said to act
Couple
2 equal and opposite parallel forces that act upon an object through different lines of action
Density
The mass per volume of a material (kgm^-3)
Drag
The frictional force that an object experiences when moving through a fluid
Equilibrium
The resultant moment and force=0
Friction
The resistive force produced when there is movement between 2 surfaces
Moment
Perpendicular distance x force from a pivot
Pressure
The force that a surface experiences per unit area (Pa)
Principle of Moments
In equilibrium, the sum of anti-clockwise moments + the sum of clockwise moments =0
Tension
The result of 2 forces acting on an object in opposite outwards directions
Terminal velocity
The maximum velocity an object that occurs when resistive and driving forces are equal
Upthrust
The upwards force that a fluid applies on an object
Weight
W=mg
Newton’s First Law of Motion
An object will remain at rest or constant velocity unless acted upon by an external force
Newton’s Second Law of Motion
F=ma
Newton’s Third Law of Motion
For every action, there is an equal and opposite reaction
Conservation of energy
In a closed system with no external forces, the total energy before event is equal to the total energy after event
Efficiency
Useful output/ total input
Gravitation potential energy (gpe)
The energy gained by an object when it is raised in a gravitational field
Kinetic energy
The energy an object has due to its motion
Power
The work done by a system/ time taken
Work done
The energy transferred when a force moves an object over a distance
