Topic 4- Forces And Energy Flashcards
System
A single object or a group of objects you’re interested in
What happens when a system changes?
Energy is transferred, it can be transferred into or away from the system between different types of energy stores
Closed system
Defined so that the net change in energy is zero
Work done
When a force moves an object through a distance work is done on the object and energy is transferred
Power
The rate of energy transfer, how much work is being done every second
What unit is power measured in?
Watts (W)
1W = 1 J/s
A force
Is a push or pull on an object that is caused by it interacting with something
Contact force
Objects need to be touching for a force to act
Eg. Friction between a cars tyre and the road
Non-contact force
Forces that can act between objects that aren’t touching
Eg. Gravitational attraction between the sun and earth
Interaction pair
Whenever two objects interact both objects feel an equal but opposite force (newtons 3rd law) the pair of forces are called an interaction pair
Free body diagram
Shows all the forces acting on an object
Resultant force
Overall force on a point or object
Moment
A turning effect of a force
