Free Particle Model Quiz 1:
Qualitative Force Diagrams
Make a force diagram for each of the following, including:
a) Force vectors, clearly labeled
b) Qualitatively correct force vector lengths with equality marks on vectors and component
vectors as needed.
Note: Both complete and shorthand labels for force vectors were provided in this key.
1. Make a force diagram for the backpack which is being dragged at constant speed.
7th grader’s
backpack
7th grader
floor
2. Make a force diagram for the sunbather (at rest).
Grassy Hill
Sunbather
Bake me,
nasty sun.
©Modeling Instruction 2013 1 U4 Freeparticle - quiz1 v3.1
y =
x
F
normal, on backpack, by floor
F
gravity, on backpack, by earth
F
net
= 0
F
N, b, f
F
g, b, e
= F
friction(kinetic), on backpack, by floor
F
tension, on backpack, by 7th grader
F
fk, b, f
F
T, b, 7
F
g,s,e
F
N,s,h
F
net
= 0
x