SCHOLAR START
11-25-13
GENERALS CAN:
EXPLAIN HOW BALANCED AND
UNBALANCED FORCES AFFECT
THE MOTION OF FALLING
OBJECTS.
Evaluate the following statements and decide if they fit
Newton’s 3rd Law: Put them into two columns.
A. You push on a tree with your hand and the tree pushes
back on your hand.
B. A small car tows a large truck and they move at a
constant speed. The truck pulls back on the car and the
car pulls on the truck.
C. A small car tows a large truck and they speed up. The
truck pulls back on the car and the car pulls on the truck.
D. The earth pulls down on you (your weight) and the floor
pushes up on you.
E. Billy pushes Johnny and causes Johnny to fall down.
Johnny exerts a force on Billy and Billy exerts a force on
Johnny.
F. You pull on the door of the classroom and the door
opens. Your hand exerts a force on the door and the
door exerts a force on your hand.
G. A horse is pulling a cart and the cart is speeding up. The
horse exerts a force on the cart and the cart exerts a
force on the horse.
H. You hold a book against the wall. You apply a force to
the book and the wall applies a force to the book.
FARMER BROWN AND HIS STUBBORN HORSE
GROUP CHALLENGE- LET’S SEE WHO
FIGURES IT OUT FIRST!!
C’mon old
horse, please
pull the wagon!
It’s not
Physic-ally
possible.
DIRECTIONS FOR POSTING:
• GO TO MY WEBPAGE- MSHERBERGSSCIENCE.WEEBLY.COM
• CLICK ON THE LINK TO THE PADLET PAGE (ON THE HOME PAGE)
• TYPE INTO THE FARMER/DOBBIN’S PAGE- POST ANYWHERE
YOU’D LIKE BY DOUBLE CLICKING!
NEWTON’S
RD
3
LAW RECAP:
• FOR EVERY ACTION, THERE IS AN EQUAL AND OPPOSITE
REACTION.
• FORCES OCCUR IN PAIRS
• THE ACTION-REACTION
OBJECT!!!
FORCES DO NOT ACT ON THE SAME
EXIT
EXPECTATIONS
• CHAIRS PUSHED IN
• AREA PICKED UP (IF YOU DON’T PUT THINGS ON THE
FLOOR, IT’S MUCH EASIER TO PICK IT UP!)
• DESKS STRAIGHTENED
What’s Due:
Lab Analysis- Balloon lab
Calculating Acceleration
- Missing a lot of penny labs- if
you have that, turn it in!
SCHOLAR START
11-26-13
GENERALS CAN:
EXPLAIN HOW BALANCED
AND UNBALANCED
FORCES AFFECT THE
MOTION OF FALLING
OBJECTS.
2 minutes
Describe the forces acting on
the objects and explain why the
truck is able to tow the
jeep/trailer. *note that the mass of the
truck is not greater than that of the trailer.
1. THE ELEPHANT AND THE FEATHER EACH HAVE THE SAME FORCE OF GRAVITY.
2. THE ELEPHANT HAS MORE MASS, YET BOTH ELEPHANT AND FEATHER EXPERIENCE
THE SAME FORCE OF GRAVITY.
3. THE ELEPHANT EXPERIENCES A GREATER FORCE OF GRAVITY, YET BOTH THE
ELEPHANT AND THE FEATHER HAVE THE SAME MASS.
4. ON EARTH, ALL OBJECTS (WHETHER AN ELEPHANT OR A FEATHER) HAVE THE
SAME FORCE OF GRAVITY.
5. THE ELEPHANT WEIGHS MORE THAN THE FEATHER, YET THEY EACH HAVE THE SAME
MASS.
6. THE ELEPHANT CLEARLY HAS MORE MASS THAN THE FEATHER, YET THEY EACH
WEIGH THE SAME.
7. THE ELEPHANT CLEARLY HAS MORE MASS THAN THE FEATHER, YET THE AMOUNT
OF GRAVITY (FORCE) IS THE SAME FOR EACH.
8. THE ELEPHANT HAS THE GREATEST ACCELERATION, YET THE AMOUNT OF GRAVITY
IS THE SAME FOR EACH.
FREE FALLING….
ALL OBJECTS REGARDLESS OF THEIR MASS, FREE FALL WITH THE SAME
ACCELERATION: 9.8 M/S2. THIS PARTICULAR ACCELERATION VALUE IS SO
IMPORTANT IN PHYSICS THAT IT HAS ITS OWN PECULIAR NAME - THE ACCELERATION
OF GRAVITY - AND ITS OWN PECULIAR SYMBOL - G.
BUT WHY DO ALL OBJECTS FREE FALL AT THE SAME RATE OF ACCELERATION
REGARDLESS OF THEIR MASS? IS IT BECAUSE THEY ALL WEIGH THE SAME? ... BECAUSE
THEY ALL HAVE THE SAME GRAVITY? ... BECAUSE THE AIR RESISTANCE IS THE SAME
FOR EACH? WHY? LET’S THINK ABOUT THIS AS WE FINISH OUR AIRPLANE ACTIVITY!
AIRPLANE CRASH- 
HOW ARE NEWTON’S LAWS AT WORK IN THIS
AIRPLANE CRASH? WHY DIDN’T THE FORCE OF AIR
RESISTANCE HOLD THE AIRPLANE UP IF THE FORCES ARE
EQUAL AND OPPOSITE? (THE FORCE OF THE PLANE
PUSHING AGAINST THE AIR AND THE FORCE OF THE AIR
PUSHING AGAINST THE PLANE.)
LET’S FINISH FIGURING OUT OUR THEORY FOR
THE CRASH- HOW DID IT HAPPEN?
SMALL GROUP WORK- FINISH
YOUR AIRPLANE PAPERSELECT GROUPS (CHOSEN AT
RANDOM BY THE STICK PICK)
WILL BE PRESENTING THEIR
FINDINGS, SO MAKE SURE YOU
CAN EXPLAIN YOURSELF WELL!
What’s Due:
-Lab Analysis- Balloon lab
-Calculating Acceleration
-Missing a lot of penny labs- if
you have that, turn it in!
-Airplane Crash worksheet
In the Near Future:
Seatbelt Persuasive letter
(December 6th)
Motion and Forces Unit Test
(December 13th)
Fall Final Exam- study guide will
be available
(December 17th)