Work, energy and power Flashcards
Define Gravitational potential energy
The energy an object possesses due to its position relative to a reference point.
Define Kinetic energy
The energy an object has as a result of the object’s motion
Mechanical Energy
The sum ofgravitational potential and kinetic energy at a point.
What is the priciple of conservation of mechanical energy
In the absence of air resistance or any external forces, the mechanical energy of an object is constant.
Law of conservation of energy
The total energy in a system cannot be created nor destroyed; only transfonned from one fom to another
define work done
The product of the displacement and the component of the förce parallel to the displacement
What is positive work
if a force acts in the same direction as the motion of an object the work done is positive (energy gained)
only components of the force parallel to the direction of the motion do work (horizontal component)
When is work done negative
if energy is lost by the object work done is negative
work done is the opposite direction of motion
When is no work done
if a force acts perpendicular to the direction of motion
What is important to remember when calculating work
Only include forces act in the same (opposite) direction
don’t add gravitational force, normal force or vertical components as these are perpendicular to the direction
What happens when an object moves on a slope
work is done by gravity
What is work done by gravity expressed as
potential energy and the height= sindelta x
What is the work energy theorem
The work done by a net force on an object is equal to the change in kinetic energy
Define power
The rate at which work is done or the rate at which energy is transferred.
What is watt
unit of power. One watt is defined as the power when one joule of work is done
