motion & forces

Amusement Park Forces

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?

Can you think of examples of forces?

Balanced Forces?

Unbalanced Forces?

What is a Force?

GRAVITYGRAVITY: An attraction force between all masses

Newton’s universal law of Newton’s universal law of gravitationgravitation: 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 forceforce

The greater the distancedistance, the lessless the force

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

What is Gravity?

Gravity in Space

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

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 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?

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

InertiaInertia 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 earthb)guns being firedc) 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

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 Law of conservation of

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

Rollercoaster Momentum