04 Work And Energy Flashcards
When is mechanical work done?
When a force moves an object.
When someone kicks a ball, is the work done positive or negative?
Positive
When someone catches a ball, is the work negative or positive?
Negative
What is the S.I unit for work done?
Joules (J)
Is energy a vector or scalar quantity?
Scalar
When calculating work done what is the force equal to?
The weight of the object
What is the effect a force has in a particular direction called?
The component
What is required to calculate a component?
A component triangle
What is a component triangle?
A right angle triangle in which the force forms the hypotenuse.
What is work measured in?
Joules (J)
What are the 3 categories of energy?
-electromagnetic energy
-kinetic energy
-potential energy
What is potential energy?
Energy stored within a system as a result of position or condition
What is kinetic energy?
Energy of motion
What does the principle of the conservation of energy state?
Energy cannot be created or destroyed. It can only be changed from one form to another.
What is power?
The work done per unit time.
What is the unit for power?
Watts (W)
What error are set squares used to eliminate?
Parralax error
What is the work energy principle ?
The change of energy of an object is equal to the net work done on the object.
When calculating work done what can you substitute weight into?
Force (F)
What is efficiency?
Useful power output.
What is the force of an engine (thrust) equal to?
The sum of all the resistive forces (friction and air resistance)
In a force distance graph, what is the area under the line equal to?
Work done
What is thinking distance?
The distance a vehicle will travel from the time that the driver thinks about pressing the break to when the break is actually pressed.
What is breaking distance?
The distance a vehicle will travel from the point where it’s brakes are fully applied to when it comes to a complete stop.
What is stopping distance?
The total distance travelled when stopping a vehicle.
What is the equation for stopping distance?
Thinking distance + braking distance
What is force x distance?
Work done
Is work a vector or scalar quantity?
Scalar
What is the definition of work?
Force applied multiplied by the displacement in the direction of the force
