Slide 1: Motion & Forces Amusement Park Forces What is a Force? : FORCE = Any push or pull which causes something to move or change its speed or direction What is a Force? 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. Amusement Park Forces What is a Force? What is a Force? : Can you think of examples of forces?
Unbalanced Forces? What is a Force? What is Gravity? : 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? What is Gravity? : The greater the mass, the greater the force
The greater the distance, the less the force What is Gravity? Gravity in Space Slide 8: 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) Slide 9: Weightlessness – free from the effects of gravity Gravity by Brainpop : Gravity by Brainpop ) How does the gravity on the moon compare to the gravity on Earth?
) Why don’t you notice your own gravitational pull on the Earth?
) On what two things does the force of gravity depend? Slide 11: 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
Terminal velocity is the highest velocity that an object will reach as it falls Slide 12: Regular gravitational force With air resistance What is Motion? : 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? : What is Motion? = distance
time What is Motion? : What is Motion? What is Motion? : What is Motion? Acceleration = final speed – starting speed What is Friction? : 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 is Friction? What are some ways athletes uses friction? Acceleration by Brainpop : Acceleration by Brainpop ) What units are used to measure speed?
) What units are used to measure acceleration?
) What is another way to say “slowing down” in terms of acceleration? Slide 22: Newton's Laws of Motion Slide 23: 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 Newton's Laws of Motion Slide 24: 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 : 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 : Examples of Newton’s 1st Law Slide 28: 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. Newton's Laws of Motion The player in black had more acceleration thus he hit with a greater amount of force Slide 29: 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) Newton's Laws of Motion Examples of Newton’s 2nd Law : 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 Examples of Newton’s 2nd Law : Examples of Newton’s 2nd Law The second law states that unbalanced forces cause objects to accelerate.
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. Slide 33: third law: For every action force, there is an equal and opposite reaction force. (Forces are always paired) Newton's Laws of Motion Examples of Newton’s 3rd Law : Examples of Newton’s 3rd Law rockets leaving earth
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 Examples of Newton’s 3rd Law : 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 : Examples of Newton’s 3rd Law Slide 39: 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 Newton’s Laws by Brainpop : Newton’s Laws by Brainpop ) Why does a ball roll across a rug and come to a stop?
) What is a net force?
) Give an example of Newton’s 3rd Law: Force by Brainpop : Force by Brainpop ) What famous physicist are units of force named after?
) What does velocity measure?
) If Moby has a mass of 50 kg and Tim has a mass of 40 kg, who would require more force to move?