Download 1st Law An object will not change its speed or direction unless an

1st Law
 An object will not change its speed or direction unless an unbalanced force affects it
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Law of Inertia
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If balanced forces act on an object it doesn’t accelerate or change direction – this
doesn’t mean it doesn’t change its velocity and it doesn’t have momentum

If you slide a hockey puck on ice, eventually it will stop, because of friction on the ice. It
will also stop if it hits something like a players stick or goal post

If you kicked a ball in space, it would keep going forever, because there is no gravity,
friction or air resistance going against it. It will only stop going in one direction if it hits
something like a meteorite or reaches the gravity field of another planet

If you are driving in your car at a very high speed and hit something like a brick wall or a
tree, the car will come to an instant stop, but you will keep moving forward. This is why
cars have airbags, to protect you from smashing into the windshield
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Basically, if an object is in motion, it keeps going unless something stops it. What are
examples of outside forces that affect inertia? Most anything in the real world--gravity,
the surface of the playing field, a defensive player, or the braking action of an athlete's
body to stop.

To achieve skilled movements, athletes must effectively combine linear and angular
motion. For example, a discus thrower's body must move in a straight path from the
back to the front of the ring while rotating with increasing velocity.

When two or more motions are required, athletes must execute movements
continuously in sequence. For example, if a javelin thrower hesitates or stops at the end
of the approach just prior to the throw, the advantage of the the approach is lost.
Athletes can increase mass and/or velocity to realize proportional gains in
momentum. For example, if a football player gains both weight and speed, it is more
difficult for an opposing player to alter his path.

Transfer momentum efficiently from each segment to the whole body. For example, a
sprinter coming out of the starting blocks uses the driving action of his or her arms to
contribute to the total momentum and direction of the body.
2nd Law
 Acceleration is produced when an unbalanced force acts on an object (mass).

The more mass the object has the more net force has to be used to move it.

If you use the same force to push a truck and push a car, the car will have more
acceleration than the truck because the car has less mass.

It is easier to push an empty shopping cart than a full one, because the full shopping cart
has more mass than the empty one. This means that more force is required to push the
full shopping cart.

The Law of Acceleration

If a baseball player hits a ball with double the force, the rate at which the ball will
accelerate (speed up) will be doubled.

Football players can slow down, stop, or reverse the direction of other players
depending upon how much force they can generate and in which direction.

Acceleration is proportional to force. For example, a sprinter increases acceleration by
increasing the force that he applies against the track. Increasing force by 10% causes a
10% increase in acceleration. If he could lose fat weight but maintain the same level of
force (power), acceleration would also increase.

Maximum acceleration is achieved when all body forces are coordinated in the intended
direction. Body actions that do not contribute to a skill should be minimized to prevent
wasted energy or detract from productive movements. For example, a swimmer
coordinates the body actions to generate maximum force while minimizing unnecessary
movements that cause excessive bobbing or lateral deviations.

When rotating, lengthening the radius slows the rotation and shortening the radius
increases rotation. For example, a diver rotates faster when the tuck is tightened,
creating a shorter body radius. A pike produces slower rotation because the radius is
longer.

When jumping, the path in the air is set upon take off. Once a long jumper is in the air,
his or her arms or legs may cause body rotation, but the flight path is not affected.

Weight is the measure of force of the gravity on mass

W = mg or F=ma
3rd Law
 For every action there is an equal and opposite reaction

The force of the bug on the windshield is equal and opposite to the force of the
windshield on the bug

When you jump off a small rowing boat into water, you will push yourself forward
towards the water. The same force you used to push forward will make the boat move
backwards

When air rushes out of a balloon the opposite reaction is that the balloon flies up

When you dive off of a diving board, you push down on the springboard. The board
springs back and forces you into the air.
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The Law of Counterforce

A swimmer propels herself through the water because the water offers enough
counterforce to oppose the action of her hands pushing, allowing her to move.

An athlete can jump higher off a solid surface because it opposes his body with as much
force as he is able to generate, in contrast to sand or other unstable surface.

Maximize counterforce with stable surfaces. If a surface is stable, it offers the same
amount of force back as is generated against it. The less stable the surface, the less
counterforce is returned. For example, sand does not offer a stable surface for running
as compared to a concrete surface.

To achieve maximum jumping height, push directly downward upon take off. The
direction of counterforce is directly opposite that of the applied force, and the applied
force is most effective when it is perpendicular to the supporting surface because "give"
is minimized.

Maximize total force. When batting (or for other striking skills), the total force at impact
depends upon the both the momentum of the bat and the momentum of the ball.

Stay in contact with the ground. In activities involving throwing, pushing, pulling, or
striking, one or both feet should be kept in firm contact with the ground until the force
application is complete.