Comparison of weight and mass mass – measure of the amount of material in an object measure of an object’s inertia units – g, kg Measured by placing an object of unknown mass on a balance and comparing to an object of a standard known mass 20 kg
Comparison of weight and mass weight – measure of the pull of gravity on an object units – N Measured by placing an object on a spring scale to measure the downward pull of gravity
Calculating weight Fg = Fw = ma = mg Weight is the scalar of Fg and is found by multiplying an object’s mass times the acceleration due to gravity
“weightlessness” escape velocity –the minimum speed required to escape the pull of gravity, 11 km/s. microgravity – objects in free fall appear to be “weightless” because there is no normal force to balance gravitational force. http://galileoandeinstein.physics.virginia.edu/more_stuff/Applets/newt/newtmtn.html