Mass vs. Weight
Homework:
Read 4.6-4.9 and be prepared for
a brief quiz Tomorrow
Relationship between Mass and
Weight
Mass and weight are related, but they are
not the same.
Fw = mg
Ex. : Fw = (2 kg)(-10 m/s2)
= -20 N
In words: The force of weight equals mass
times the acceleration due to gravity
Mass vs. Weight
You will be able to differentiate between
mass and weight…
Apparent weight – force exerted by a scale
Weightlessness – an apparent weight of
zero
W = Fg = mg
Weight
mass
1 kg
=
10 N
Example Problem:
Your mass is 75 kg. You stand on a scale in
an elevator that is going up at 2.0 m/s2.
A) What is your weight (before entering the
elevator)?
B) What is your apparent weight (on the
elevator?
C) Is this larger, smaller, or equal to your
weight at rest?