1. Why object remain stationary
Static Equilibrium
Why object remain stationary

2. Static Equilibrium An object is in static equilibrium if:
It has zero velocity
The net force acting on the object is zero
The net torque acting on the object is zero
Mathematically speaking
V=0, Fnet =0, Tnet=0
The first two conditions make sense, an object is not moving if the net force acting on it is zero. Why does the net torque need to be zero? (demo)

3. Solving Static Problems
Draw the FBD of the body. Do not draw the body as a dot but instead show the relative positions of all the forces
Choose an x-y coordinate system
Resolve into components any forces that are at angles
Write a net force equation for both the x and y direction
Choose a pivot point
Write a net torque equation based on the pp
Solve the equation (max of 3)

4. Center of Mass
If a solid object such as the board in the previous question has a mass…..we treat it as if all its mass were concentrated at one point. (center of mass)
Regular shaped objects – center of mass
Irregular shaped objects – use calculus to find. We will not do this. 