Work and conservation of energy Flashcards
What does a force rely on to work?
Motion
What quantity is work done?
Scalar
How do you calculate the work done?
You need to know the constant force applied and the distance the object has travelled in the direction of the force.
How do you calculate the work done when a force is acting at an angle to the distance in which the object is moving?
We have to use F=cosθx, where F is the component of the force in the direction of travel x distance moved.
What is the S.I unit for work?
Jules or Nm
What is the S.I derived unit for work?
kgm^2s^-2
What is often equal to the work done on the object?
The energy transferred E=W
What happened in relation to Ek and Ep and what is this providing doesn’t happen ?
Ep=Ek, mgh=1/2mv^2 providing no energy is lost to it’s surroundings.
What is the principle of conservation of energy?
The total energy of a closed system remains constant- energy can’t be created or destroyed, but can be transferred from one form to another.
What units do we use to measure energy in very small amounts?
eV
What do we use when measuring very large amounts of energy?
The kWh (kilo-Watt-hour).
Define work done.
Work done is the force multiplied by the distance moved in the direction of the force. Derived S.I units are Joules.
Define a Joule.
1 Joule is the work done when a force of 1N moves it’s point of application 1m in the direction of the force.
Describe an example of conservation of energy.
When a car is moving on a hill it posses both kinetic and gravitational potential energy. The chemical energy in the fuel produces a lot of thermal energy.
Why does the total energy of a system remain the same?
Because of conservation of energy.
