Transcript Newton`s Laws

Law of Inertia
(Newton’s 1st Law)
• An object at rest remains at rest
unless acted upon by a force. An
object in motion remains in
motion, and at a constant velocity,
unless acted upon by a force.
• E.g. we have to overcome gravity
to jump, or tackling someone in
rugby
• http://www.youtube.com/watch?v
=Rq2Xb3BQZyY
Question
• Consider a football player who is
looking to head the ball into the
net. What must be done to
change the direction of the ball
from across the goal to towards
the goal?
A force must be applied greater
than the inertia of the ball so its
direction can be changed
Consider what would happen if
the ball was heavier? Or lighter?
F = MA
(Newton’s 2nd Law)
When a force is applied to a mass,
the result is acceleration of that
mass in the direction the force is
applied.
The greater the force applied to a
mass the greater the acceleration
http://www.youtube.com/watch?v=
VieEzw14h_Y
In a golf context…..
The golf ball has it’s own inertia
and it needs to be acted upon by a
force to move the ball.
The force is created through the
swinging of the club.
Where the force is applied
depends on the direction of the
ball so keeping the club head on
the plane means the ball will fly
straight, not slice or pull.
What can act on the inertia of the ball to slow
it down or take it off line?
• Wind
• Gravity
• Make up of the ground e.g.
grass, sand, water trap
• Air resistance
Remember F=MA so more force is
created from a driver because of
the club head and the speed it
generates (acceleration)
Question
Consider the situation of a serve
in tennis, a kick in soccer, shot at
goal in hockey or a pitch in softball
How can we apply Newton’s
Second law to produce a more
powerful strike, throw or pitch?
The greater the initial input of
force, the greater the acceleration
of the object upon contact or
release.
The longer the lever the greater
the force at the extremity, thus
greater acceleration on the object
on contact or release
Action/Reaction
(Newtons 3rd Law)
For every action there is an equal
and opposite reaction.
What are some examples of
action-reaction in sport?
Examples
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Running
High Jump
Kicking a Ball
Hitting a ball
Punching in boxing
Sprinting
http://www.youtube.com/watch?v=FVX
vPMV9cCI
http://www.youtube.com/watch?v=By1
JQFxfLMM
In a golf context……
Every action has an equal or
opposite reaction.
So when I hit the golf ball the equal
or opposite reaction is for the ball to
fly through the air.
You can see this happening in this
video:
http://www.youtube.com/watch?v=
2Y57pw_iWlk