Newton's Third Law of Motion

Today’s special
Hw check – vocab
Test results
HW for next time:
HW I due
Newton’s Third Law of
PAe.7: Explain the motion of objects on the basis of
Newton’s three laws of motion: inertia; the relationship
among force, mass, and acceleration; and action and reaction
PAa.1: Generate hypotheses on the basis of credible,
accurate, and relevant sources of scientific information.
PAa.2: Use appropriate laboratory apparatuses, technology,
and techniques safely and accurately when conducting a
scientific investigation.
PAa.9: Use appropriate safety procedures when conducting
When a rocket blasts off, if it was
not near the ground, would it take
Newton’s Third Law
Whenever one object exerts a force
on a second object, the second object
exerts an equal and opposite force on
the first
Simple rule
Action: Object A exerts force on
object B
Reaction: Object B exerts a force on
object A
Action and reaction
Effects on objects differ if their
masses are different
a = F/m
Decreasing mass makes the
acceleration greater
Action and reaction forces act
on different objects
Forces cancel only when they act on
the same body
Donkey cart
Equal and opposite?
Donkey pulls and cart and pushes on
Bull fights
Why are they dangerous?
How does it work?
When a rocket blasts off, if it was
not near the ground, would it take
Chapter Review HW: pp. 80-82
I. Review questions2-20 even (due
date: ____________)
II. Exercises 2-20 even; Problems 18 (due date: __________)
Today’s special
HW check; Q & A
Newton’s Laws video
Lab due next time! Don’t forget to
write your conclusion
Today’s special
Turn in lab on front table
Some equations for HW II
Work on HW II with table partner
(work on problems, first!)
Handout: Newton’s 3rd Law
New seating chart
Some equations for HW II
Billy rides his bike from rest to 8 m/s
in 4 s. How much force did Billy apply
to his bike if he and his bike have a
mass of 75 kg?
Sally pushes her skateboard with a
force of 5 N. The skateboard has a
mass of 2 kg. How fast is it going
after 3 seconds?
Today’s special
Student Agenda grade (planner)
HW II check
Computer project
Practice Test on Smartresponse
system; enter answers, make
corrections before turning in next
Test 4 next time!
Today’s special
Turn in Practice test on front table
Test 4 Newton’s 3rd Law, enter MC
answer on smart response
Turn in test completed with
sentences & essays
Get Vocab 5: Momentum; work quietly
until everyone has finished their test.
Movie time!