Amusement Park Forces

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FORCE = Any push or pull which causes something to move or change its speed or direction

What is a Force?

Forces can be BALANCED or UNBALANCED

Balanced forces are equal in size and opposite in direction

UnBalanced forces are not equal in size and/or opposite in direction. If the forces on an object are UNBALANCED, we say a NET force results.

Amusement Park Forces

What is a Force?

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Can you think of examples of forces?

Balanced Forces?

Unbalanced Forces?

What is a Force?

GRAVITY: An attraction force between all masses

Newton’s universal law of gravitation: Every object in the universe exerts a gravitational attraction to all other objects in the universe

The amount of gravitational force depends upon the mass of the objects and the distance between the objects

What is Gravity?

The greater the mass, the greater the force

The greater the distance, the less the force

Acceleration due to gravity = 9.8 m/s/s or 9.8 m/s2

What is Gravity?

Gravity in Space

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Weight is a measure of the gravitational force between two objects

The greater the mass the greater the force (weight)

Measured in units called Newtons (N)

Weightlessness – free from the effects of gravity

Gravity by Brainpop

1) How does the gravity on the moon compare to the gravity on Earth? 2) Why don’t you notice your own gravitational pull on the Earth? 3) On what two things does the force of gravity depend?

http://www.brainpop.com/science/motionsandforces/gravity

Air resistance: The force of air exerted on a falling object

The air pushes up as gravity pulls down

Dependent upon the shape and surface area of the object

When the air resistance equals the force of gravity, terminal velocity is reached

Terminal velocity is the highest velocity that an object will reach as it falls

What is Motion?

Motion: A change in position of an object compared to a reference point

Motion involves all of the following:

What is Motion?

Speed The rate of change in position

Speed = distance ÷ time or

= distance time

http://www.amadirectlink.com/news/2005/images/Speed.jpg

What is Motion?

Velocity Speed plus direction

Example: 50 km/hour north

What is Motion?

Acceleration The rate of change in velocity Positive acceleration = speeding up

Negative acceleration = slowing down (decelerate)

Acceleration = Vfinal – Vinitial Time or

= ∆Velocity Time

What is Friction? Friction = A force that opposes or slows

down motion

Caused by the physical contact between moving surfaces

The amount of friction depends upon the kinds of surfaces and the force pressing the surfaces together

Changes motion into heat

What is Friction? What are some ways athletes uses

friction?

Acceleration by Brainpop

1) What units are used to measure speed? 2) What units are used to measure acceleration?

3) What is another way to say “slowing down” in terms of acceleration?

http://www.brainpop.com/science/motionsandforces/acceleration

First Law: An object at rest stays at rest or an object in motion, stays in motion (in the same direction/at the same speed) unless acted upon by an unbalanced force

Also called the law of inertia

Inertia

A property of matter

The tendency of an object to resist any change in its motion

The greater the mass the greater the inertia

The greater the speed the greater the inertia

Examples of Newton’s 1st Law

a) car suddenly stops and you strain against the seat belt b) when riding a horse, the horse suddenly stops and you fly over its head c) the magician pulls the tablecloth out from under a table full of dishes d) the difficulty of pushing a dead car e) lawn bowling on a cut and rolled lawn verses an uncut lawn f) car turns left and you appear to slide to the right

Examples of Newton’s 1st Law

Second law: The greater the force applied to an object, the more the object will accelerate. It takes more force to accelerate an object with a lot of mass than to accelerate something with very little mass.

The player in black had more

acceleration thus he hit with a

greater amount of force

Second law: The greater the force, the greater the

acceleration

The greater the mass, the greater the force needed for the same acceleration

Calculated by: F = ma

(F = force, m = mass, a = acceleration)

Examples of Newton’s 2nd Law

a) hitting a baseball, the harder the hit, the faster the ball goes b) accelerating or decelerating a car c) The positioning of football players - massive players on the line with lighter (faster to accelerate) players in the backfield d) a loaded versus an unloaded truck

Examples of Newton’s 2nd Law

Examples of Newton’s 2nd Law

The second law states that

unbalanced forces cause

objects to accelerate with an

acceleration which is directly

proportional to the net force

and inversely proportional to

the mass. This one is telling

us that big heavy objects

don’t move as fast or as

easily as smaller lighter

objects. It takes more to

slow down a charging bull

then to slow down a

charging mouse.

third law: For every action force, there is an equal and opposite reaction force. (Forces are always paired)

Examples of Newton’s 3rd Law

a) rockets leaving earth b)guns being fired c) two cars hit head on d) astronauts in space e) pool or billiards f) jumping out of a boat onto the

dock g) sprinklers rotating

http://www.j-archive.com/media/2004-10-27_DJ_22.jpg

Examples of Newton’s 3rd Law Newton’s third law: "For every action, there is an equal and opposite reaction." When you fire a gun you feel the recoil. Some of the funniest things in cartoons follow physics that have been exaggerated or just plain ignored. Wyle Coyote hangs suspended in space over that canyon for a lot longer than an object would in reality, but it is the anticipation of the drop and Wyle's facial recognition of the upcoming pain that is so classically cartooney. So some laws are stretched for comical effect.

Examples of Newton’s 3rd Law

Momentum: The quantity of motion

A property of moving objects

Calculated by: P = mv

(p = momentum, m = mass, v = velocity)

Law of conservation of momentum: the total amount of momentum of a group of objects does not change unless outside forces act on the objects

Rollercoaster Momentum

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Newton’s Laws by Brainpop

1) Why does a ball roll across a rug and come to a stop? 2) What is a net force?

3) Give an example of Newton’s 3rd Law:

http://www.brainpop.com/science/motionsandforces/newtonslawsofmotion

Force by Brainpop

1) What famous physicist are units of force named after? 2) What does velocity measure?

3) If Moby has a mass of 50 kg and Tim has a mass of 40 kg, who would require more force to move?

http://www.brainpop.com/science/motionsandforces/force/