A look at Newton's three Laws of Motion for Year 10 Science students at Saint Ignatius College Geelong.

1. OBJECTS IN MOTION.
04. Newton’s Laws of Motion.
Ian Anderson
Saint Ignatius College Geelong

2. NEWTON’S FIRST LAW OF MOTION.
Why is the bowl of fruit
stationary on the table?
Why doesn’t it slide off or
float away?
Source: http://absorbant.rssing.com/chan-
1377193/all_p47.html

3. NEWTON’S FIRST LAW OF MOTION.
Why do we wear
seatbelts when travelling
in a car?
What would happen if we
didn’t and the car braked
suddenly?
Source: https://www.boundless.com/physics/the-laws-of-
motion/newton-s-laws/

4. NEWTON’S FIRST LAW OF MOTION.
“Every body continues in its state of rest or of uniform
motion in a straight line unless it is compelled to change
this state by forces acting on it.”
Or in plain speak …
An object will keep doing what its already doing until a
force acts on it.
“The Law of Inertia”.

5. NEWTON’S FIRST LAW OF MOTION.
Do you remember what a force is?
Source: http://www.fdwallpapers.com/desktop.php?pid=1650

6. NEWTON’S FIRST LAW OF MOTION.
A force is any push, pull or twist that causes an object to do
any of the following:
 increase its speed (accelerate).
 decrease its speed (decelerate).
 change its direction.
 change its shape.
Force is measured in Newtons (N).
Source: http://en.wikipedia.org/wiki/Isaac_Newton

7. NEWTON’S FIRST LAW OF MOTION.
Why is the bowl of fruit
stationary on the table?
Answer =
 Because all the forces
are balanced i.e. the
net force = 0.
 For the bowl to slide off
the table we would
need to push it (i.e.
apply a force). Source: http://absorbant.rssing.com/chan-
1377193/all_p47.html

8. NEWTON’S FIRST LAW OF MOTION.
Why do we wear
seatbelts when travelling
in a car?
Source: https://www.boundless.com/physics/the-laws-of-
motion/newton-s-laws/

9. NEWTON’S FIRST LAW OF MOTION.
Why do we wear
seatbelts when travelling
in a car?
Answer =
If the car was to break
suddenly, we would
continue moving forward
unless restrained by a
seatbelt.
Source: https://www.boundless.com/physics/the-laws-of-
motion/newton-s-laws/

10. NEWTON’S SECOND LAW OF MOTION.
“The acceleration of an object is directly proportional to the
net force applied and inversely proportional to its mass.”
Or in plain speak …
The acceleration of an object will
be greater, the lighter the object
and the larger the net force
acting on it.
Source: http://tdion.edublogs.org/2009/12/15/newtons-laws/

11. NEWTON’S SECOND LAW OF MOTION.
𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 =
𝐹𝑜𝑟𝑐𝑒
𝑚𝑎𝑠𝑠
Which can be written as,
𝐹𝑜𝑟𝑐𝑒 = 𝑚𝑎𝑠𝑠 × 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛
𝐹𝑛𝑒𝑡 = 𝑚 × 𝑎
Source: Rickard et al. (2006)

12. MASS V WEIGHT.
Is there a difference between mass and weight?
Weight is the force of gravity acting on an object.
𝑊𝑒𝑖𝑔ℎ𝑡 = 𝑚𝑎𝑠𝑠 × 𝑔𝑟𝑎𝑣𝑖𝑡𝑦
𝑤 = 𝑚 × 𝑔
Where 𝑔 = 9.8 m/s2 (on earth).

13. MASS V WEIGHT.
If Elvis’ mass is 100kg, what is his weight on Earth and on
the moon?
 Earth gravity = 9.8 m/s2 & Moon gravity = 1.6 m/s2
𝑤 = 𝑚 × 𝑔
On Earth
𝑤 = 100 𝑥 9.8
= 980 N.
On the moon
𝑤 = 100 𝑥 1.6
= 160 N.
Source: http://howthingsfly.si.edu/media/moon-scale

14. NEWTON’S THIRD LAW OF MOTION.
“For every action (applied force) there will be a reaction
(response force) that will be the same size as the action
force and in the opposite direction to the action force.”
Or in plain speak …
If you push on something it will
push back on you.
For every action there is an equal
and opposite reaction.
Source: Rickard et al. (2006)

15. BIBLIOGRAPHY.
Rickard, G., Phillips, G., Ellis, J., Jeffery, F., &
Roberson, P. (2006). Science Dimensions 4:
Coursebook. Melbourne: Pearson Education
Australia.

16. http://SICkScience10.wikispaces.com/