Mechanics Flashcards
What is the Centre of Gravity?
A point where the weight of an object appears to act.
What does the Conservation of Energy state?
Energy cannot be created or destroyed, it can only be transferred from one store to another
What is the principle of Conservation of Momentum?
The momentum before an event equals the momentum after the event provided that no external force acts
Define Drag.
The resistance against the motion of an object through a fluid, usually proportional to the object’s speed.
How is Efficiency calculated?
The useful output of a system divided by the total input.
What characterises an Elastic Collision?
The kinetic energy of a system before an event equals the kinetic energy after the event.
What does Equilibrium mean in physics?
Sum of the forces equals zero AND the sum of the clockwise moments equals the sum of the clockwise moment
What is Force?
The rate of change of momentum of an object.
Define Friction.
The resistance against the motion of an object, caused by air or surface contact.
What is Gravitational Potential Energy?
The energy an object possesses by virtue of its position in a gravitational field.
What is Impulse?
The change of momentum of an object when a force acts on it; equal to the area under a force-time graph.
What defines an Inelastic Collision?
The kinetic energy of a system before an event is not equal to the kinetic energy after the event.
What is Kinetic Energy?
The ability of an object to do work by virtue of its motion
What is Lift?
A force acting perpendicular to the flow of air or liquid around an object, typically upwards.
Define Moment of a force
The product of a force and the perpendicular distance from the line of action of the force to the pivot.
What is Momentum?
The product of an object’s mass and its velocity.
State Newton’s First Law.
An object will remain at constant velocity or at rest unless acted on by a resultant external force.
What does Newton’s Second Law state?
Resultant force is proportional to rate of change of linear momentum
State Newton’s Third Law.
If object A exerts a force on object B, then object B exerts an equal and opposite force of the same type on object A
How is Power defined?
The rate that energy is transferred; rate of work done
What is Resultant Force?
The sum of all forces acting on an object.
Define Scalar.
A quantity with only magnitude only
What is Terminal Velocity?
The maximum velocity an object can achieve when frictional and driving forces or weight are balanced.
Define Vector.
A quantity with magnitude and direction
What is Weight?
The force of gravity on an object; the product of mass and gravitational acceleration.
Fill in the blank: Work Done is when…
A force is moved in the direction of the force.
Define Impulse
Change in momentum of a body
Change in momentum of a body equals
Final momentum - initial momentum
Define Gravitational Field Strength
Force per unit mass on an object placed in a gravitational field
Define the principle of moments
If a system is in equilibrium, the sum of the clockwise moments must equal the sum of the anticlockwise moments
Define a joule
The amount of work done when a force of one newton is moved through one metre
Define energy
The ability to do work
Define Elastic Potential Energy
EPE is the ability of an object to do work by virtue of a change in its shape
Define power
Rate of work done OR rate of energy transferred.
Define a Watt
Rate of transfer of energy of one joule per second.
