Chapter 5: Work, Energy and Power Flashcards
What is Work done?
Work done is the amount of energy transferred when a force is applied to an object over a certain distance.
What is the equation which links Work, Force and Distance?
Work = Force x Distance moved in the direction of the Force.
How do you calculate Work Done when a force is applied at an angle?
To calculate the work done when a force is applied at an angle, calculate the component of the force applied in the direction of motion and multiply by the distance travelled in the direction of motion.
Work = Fx cosθ
What is the definition of ‘Energy’?
Energy is the capacitance to do work.
What types of energy can energy systems associated be mass be classed under?
Energy of systems with mass can either be classed as Kinetic Energy or Gravitational Potential Energy.
What is Kinetic Energy, and how can it be calculated?
Kinetic Energy is energy associated with the motion of an object, and can be calculated by using the equation: KE = ½mv²
What is Gravitational Potential Energy, and how can it be calculated?
Gravitational Potential Energy is the energy associated with an object due to its position within a Gravitational Field, and can be calculated using the equation: GPE = mgh.
What is the Principle of Conservation of Energy?
The Principle of Conservation Energy states that the total energy within a closed system remains constant, that energy cannot be created or destroyed and can only be transferred from one form to another.
What is the equation when Kinetic and Gravitational Potential Energy are exchanged?
As Kinetic Energy and Gravitational Potential Energy are exchanged, their equations become equal to each other. The resulting equation would be:
½mv² = mgh
What is the definition of Power, and how can it be calculated?
Power is defined as the Work Done over Time (or Energy Transferred over Time), and can be calculated using the equation: Power = Work Done / Time.
Work Done can be KE, GPE or Fd.
What is the Unit and SI Units for Power?
The Unit for Power are Watts (W), and the SI Unit is Js¯1
What is the equation for Power when there is a constant force being applied?
When a constant force is being applied, Work Done can be substituted with Fd to create the equation:
Power = Fd / t = Fv (where ‘v’ is equal to the velocity).
What is the definition of Efficiency?
Efficiency is defined as a ratio of Useful Output Energy to the Total Output Energy, expressed as a percentage.
How do you calculate Efficiency?
To calculate Efficiency, you find the useful output energy over the total output energy, and times by 100 to get a percentage.
Efficiency = (Useful Energy / Total Energy) x 100
