Which object is in static equilibrium?

a rolling ball that has a net force acting on it
a cruising car that has no net force acting on it
a book that has no net force acting on it and is sitting on a table
a vase that has a net force acting on it and is sitting on a shelf

Question

Which object is in static equilibrium?

a rolling ball that has a net force acting on it
a cruising car that has no net force acting on it
a book that has no net force acting on it and is sitting on a table
a vase that has a net force acting on it and is sitting on a shelf

osprey · Answer

rolling balls are moving so they're not static cruising car is in dynamic equilibrium a book minding it's own business is pretty static. a vase with a net force on it is accelerating http://perendis.webs.com

sooobored · Answer

simply put 
static- stationary 
dynamic- moving

osprey · Answer

yup

vipulrakta · Answer

static equlibrium simply means net force acting on a body is zero fo$$\sum_{i=1}^{n}fi=0$$