Free Body Diagrams and Equilibrium Flashcards
What is a moment?
Concept of a force that tends to cause an object to turn
What are the steps in creating a decent free body diagram?
- identify the system
- isolate the system
- determine how the system interacts with its surroundings
- identify all the unknown forces (and moments) acting on the system
Forces acting on rigid bodies are divided into two categories, these are…
external forces
internal forces
What are common types of planar supports?
- Flexible cable, belt, chain or rope
- Smooth surfaces
- Rough surfaces
- Roller supports
- Freely sliding guide
- pin connection
- built in fixed support
- gravitational attraction
- spring action
What reaction forces an a flexible cable, belt, chain or rope support?
Always a tension directed away from the body along the direction of the cable
what reaction forces can a smooth surface support?
Contact force is compressive and its normal to the surface (plane of contact)
what reaction forces can a rough surface support?
Rough surfaces are capable of supporting a tangential component F as well as a normal component N of the resultant
what reaction forces can roller supports support?
compressive force normal to the supporting surface
what reaction forces can a free sliding guide support?
can support force normal to guide only
what reaction forces can a pin connection support?
capable of supporting a force in any direction in the plane normal to the pin axis
what reaction forces can a built in or fixed support support?
an axial force, transverse (sheer) force and a bending moment to prevent rotation
what reaction forces does the force of gravity support?
acts towards the centre of the earth from the centre of mass of the object
what reaction forces can a spring support?
spring force is tensile if stretched and compressive if compressed
If a system is in equilibrium,…
it is in a state of balance
whats special about linear and angular momentum for a system in equilibrium?
they’re unchanging
