balanced and un balanced nlc slide

2. BALANCED AND
UNBALANCED
FORCES
LESSON 1

3. COMPONENT 1: SHORT REVIEW
Key Idea
• Net Force is the sum of all the forces
acting on an object; When the forces
acting on an object are balanced,
there is no net force (F net) and so
the object will not move. When the
forces acting on an object are
unbalanced, there is net force (F net)
and so the object will move.

4. • The lesson is about balanced and unbalanced
forces and how forces can affect the way an
object moves. The lesson may also help
student to be better at using symbols to
communicate information in science.
COMPONENT 2: LESSON PURPOSE

5. COMPONENT 3: LESSON LANGUAGE PRACTICE
FORCE SAME DIRECTION
OPPOSITE
DIRECTION
CANCEL
REPRÉSENTATIONS SITUATIONS

6. Balance and Forces
Here are two statements about forces and
balance:
1. Equal forces acting in opposite directions
in the same line cancel each other and are
described as being ‘in balance’.
2. The movement of objects is changed if
the forces acting on them are not ‘in
balance’.

7. These statements relate to four representations
of forces (⇨ or ⇦) acting on some square
objects (■, ■, ■, and ■,) as shown here:
Situation 1 Situation 2
Situation 3 Situation 4

8. EXAMPLES OF BALANCED FORCES

9. EXAMPLES OF UNBALANCED FORCES
Tug of war See-saw
Kicking a ball

10. LET’S GET
ROLLING!
LESSON 2

11. BUILDING A FORCE
DETECTOR A FORCE IS AN INFLUENCE OR INTERACTION
THAT CAUSES AN OBJECT TO CHANGE ITS VELOCITY. A
FORCE CAN BE A PUSH OR A PULL. TWO STUDENTS
DECIDED TO TRY TO BUILD A MODEL THAT WOULD
ALLOW THEM TO SHOW THAT A FORCE ACTING ON AN
OBJECT MUST EXIST, EVEN IF YOU CANNOT SEE IT. TO
TEST THEIR THINKING, THEY CONDUCTED AN
EXPERIMENT TO SEE IF A FORCE CAN BE DETECTED BY
THE EFFECT OF THE FORCE ON AN OBJECT’S MOTION.

12. HERE ARE SOME PICTURES OF THEIR EXPERIMENT:
THEY USED THREE IDENTICAL TOY CARS TO BE
LAUNCHED FROM THE SAME STARTING POINT TO RUN
ON THREE IDENTICAL TRACKS. THE ONLY THING THEY
CHANGED WAS THE ANGLE OF THE LAUNCH RAMPS
BECAUSE THEY KNEW THAT THE FORCE OF GRAVITY
ACTING ON EACH CAR IS THE SAME – BUT BY USING A
DIFFERENT ANGLE FOR EACH CAR, THEY COULD
ACCELERATE EACH CAR DIFFERENTLY.

13. THEIR TEACHER SAID TO THEM
“WITHOUT THE FORCES OF FRICTION AND AIR RESISTANCE
TO SLOW THE CARS, THE CARS WOULD JUST KEEP
RUNNING RIGHT A CROSS THE FLOOR UNTIL THEY HIT
SOMETHING! HOWEVER, THE EXPERIMENT WILL BE VALID
BECAUSE FRICTION AND AIR RESISTANCE WOULD BE THE
SAME FOR EACH CAR BECAUSE THEY USED IDENTICAL
CARS.”. THE STUDENTS COLLECTED THEIR DATA:

14. EXPERIMENTAL
DATA DISTANCE CARS TRAVEL (CM)
Car Ramp
Ave distance angle travelled
Trial 1
Trial 2
Trial 3

15. INFORMATION
ABOUT INERTIA
LESSON 3

16. NEWTON’S FIRST LAW
Newton’s First Law – the Law of Inertia: An
object at rest will remain at rest until it is
acted upon by an unbalanced force, and an
object in motion will remain in motion unless
it is acted on by an external force.
A non-scientific meaning of Inertia: A tendency
for an organization to do nothing or to remain
unchanged.

17. THE FOLLOWING ARE ALL EXAMPLES OF EVERYDAY SITUATIONS
THAT CAN BE USED TO DESCRIBE THE LAW OF INERTIA:
1. A shinny glass marble rolling over a smooth flat floor.
2. A bicycle moving forward even after peddling is stopped.
3. A drinking glass sitting on a table.
4. Rolling a heavy tenpin ball straight down the center of a
bowling alley lane.
5. The motion of a heavy tenpin ball as it knocks the pins over.
6. A golf ball sitting on a golf tee before the golfer hits it down
the fairway.
7. A house built in an earthquake zone just before it is
destroyed by an earthquake.
8. The motion of a hockey ball that is hit along the ground
between two players.
9. A spacecraft when it is cruising between the planets Earth
and Mars.

18. • Balanced
• Unbalanced
• Rest
• Inertia
• Remain
• Gravity
• External
• Tendency
COMPONENT 3: LESSON LANGUAGE PRACTICE

19. • The lesson is about the scientific
law that explains how forces affect
the motion of objects, including the
motion of small objects like golf
balls and really large objects like
the Earth and other planets.
COMPONENT 2: LESSON PURPOSE/INTENTION

20. CRASH – FORCE
CAN MAKE THE
DIFFERENCE
LESSON 4

21. INVESTIGATING
FORCE AND MASS
LESSON 4

22. Q1. What is a crash?
ANSWER..
• When something runs into something
else.
COMPONENT 1: SHORT REVIEW
• A car crash.
• A collision.

23. Q2. What can happen in a crash?
ANSWER..
• Things can bend and twist or
snap/break/shatter.
• When a truck runs into the back of a car or
bike, the car or bike can be forces forward.
• A car crash can cause lots of damage.

24. Q3. If people are involved in a crash, what can
happen and why?
ANSWER..
• If a car hits someone, it can do a lot of damage
because it is heavier and harder than them.
People in a car crash are thrown forward
because the car stops but the people keep
going unless seatbelts save them.

25. • The lesson is about how larger forces
can cause a larger effect on other
objects. The lesson is designed to
lead students to a deeper
understanding of Sir Isaac Newton’s
Second Law involving a quantitative
relationship between Force, Mass and
Acceleration
COMPONENT 2: LESSON PURPOSE/INTENTION

26. COMPONENT 3: LESSON LANGUAGE PRACTICE
• Investigating
• Conducted
• Collisio
n
• Wondere
d
• Identical
• Mass
• Acceleratio
n
- carefully examine the facts of a situation
to find out the truth about if or how it
happened.
- An instance of one moving object or person
striking violently against another.
- led by a guide,
managed.
- similar, exactly alike.
- desire or be curious to know something.
- The measure of the amount of matter in an
object
- Is the rate of change of velocity, means
the speed is changing.

27. COMPONENT 4: LESSON ACTIVITY
One of the students who did the experiment with
toy cars in Lesson 2 decided to see what forces
can do to objects. She conducted an experiment to
see what happens when the toy cars collide with
wooden blocks – She wondered, Will the block all
get moved the same distance?
She again used three identical toy cars. She placed
three identical wooden blocks on the tracks 30 cm
from where the cars would be running on flat
ground. She made sure the cars were all the same
distance from the wooden blocks. She again used
ramps set at different angles to give each car a
INVESTIGATING FORCE AND MASS

29. The student’s teacher thought the experiment
will be valid because she used identical cars
and so any friction or air resistance would be
the same for each car.
Here are her experimental results.
EXPERIMENTAL DATA