1. 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

2. 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

3. 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

4. “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.