be considered constant

when the motion over

short distances near Earth's

surface.

But small variations occur in the acceleration

**DESPICABLE PHYSICS**

Acceleration occurs anytime an object's …

speed increases,

speed decreases, or

direction of motion changes.

Created By: Candace Le

Period One

Describing Motion

Speed

Acceleration

Velocity

Free Fall

Newton's First Law

Newton's Second Law

Newton's Third Law

Mass

Weight

Galileo versus Aristotle

Friction

The Law of Universal

Gravitation

Acceleration in Circular Motion

Projectile Motion

Linear Momentum

Free-falling objects do not encounter air resistance.

All free-falling objects (on Earth) accelerate downwards at a rate of 9.8 m/s/s

Minion

Golf Club

m = 10 kg

m = 1 kg

a =

a =

F

F

m

m

net

net

=

=

10

1

100

10

N

N

kg

kg

a = 10m/s/s

a = 10m/s/s

The dot diagram at the right depicts the acceleration of a free-falling object.

Rate of change of

distance with time.

Speed and direction

of motion.

VECTOR

SCALAR

Speedometers in cars tell us the (instantaneous) speed but not

velocity.

Speed is a measure of the distance an object travels in a given length of time:

Because only a number is given, not a directional term.

average speed =

distance traveled

time elapsed

INSTANTANEOUS SPEED:

CONSTANT SPEED:

speed at a specific instant in time

rate of change of position in which

the same distance is traveled each

second

=

The position of the object at regular time intervals is shown.

The fact that the distance that the object travels every interval of time is increasing is a sure sign that the ball is speeding up as it falls downward.

Example:

states that an object at rest tends to stay at rest; an object in motion tends to stay in motion (with the same direction and speed)

motion (or lack of motion) cannot change without an unbalanced force acting

natural tendency of objects to keep on doing what they're doing

all objects resist changes in their state of motion

"law of inertia"

Example:

acceleration is produced when a force acts on a mass

the greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object)

gives us an exact relationship between force, mass, and acceleration

F= MA

Force= Mass times Acceleration

When the smaller minion applied MORE force he was able to push off the taller minion.

the rate of change of distance with time

first derivative of distance with respect to time.

Average Speed:

Instantaneous Speed:

Average velocity is the rate of change of displacement with time. Since displacement is a vector quantity, then velocity is also a vector quantity. It has both magnitude and direction.

Velocity is not absolute, it is dependent on the observer.

average velocity =

change in position

time elapsed

measured over a non-zero time interval and

represented by the symbol v (overline)

Average velocity:

Instantaneous velocity:

the limit of average velocity as the time interval approaches zero,

the first derivative of displacement with respect to time, and

represented by the symbol v (boldface)

Displacement =

10 feet East

Direction

v=

10 feet East

t

As a vector, it must be stated with both magnitude and direction.

measured over a non-zero time interval and

represented by the symbol a (overline)

the limit of average acceleration as the time interval approaches zero,

the first derivative of velocity with respect to time,

the second derivative of displacement with respect to time, and

represented by the symbol a (boldface)

Instantaneous acceleration:

Average acceleration:

acceleration=

Δt

Δv

From

To

From

To

THE END

Rate at which velocity changes

over time.

the measure of the amount of matter

measure of resistance to acceleration (more generally, mass is a measure of resistance to all sorts of change.)

a scalar quantity associated with matter

The SI unit of mass is the kilogram [kg].

When a system is composed of several objects it is the total mass that matters.

the force of gravity on an object

Derive formula from the free fall thought experiment.

Things that weigh a newton.

Its direction is opposite the relative velocity (or intended velocity).

Dry Friction

The resistive force between clean dry solid surfaces.

Friction is normally synonymous with dry friction.

Viscous Friction

The resistive force between surfaces in relative motion through a fluid (liquids & gases).

Rolling Resistance

The resistive force experienced by rolling objects.

Since rolling does not does not necessarily involve slipping, rolling resistance is not really a form of friction.

the force between surfaces in contact that resists their relative tangential motion.

"Relative tangential motion" is a fancy way to say "slipping".

Projectile motion is a special case of two dimensional motion with constant acceleration.

The force due to gravity moderates linear motion of an object thrown at certain angle to the vertical direction.

The resulting acceleration is a constant, which is always directed in vertically downward direction.

All forces (push or pull) result from the interaction of two bodies. One body exerts a force on another. Newton's Third Law tells us that this force is exactly equal in magnitude and opposite in direction of the force we exert on the crate.

Newton's third law proclaims: to every action there is an equal and opposite reaction.

Action

Reaction

Circular Motion

Tides

Conservation of Energy

gravitational attraction exists between every pair of objects

F=G

m m

r

1 2

2

masses of the two objects

the distance between their centers

gravitational constant

due to gravity with latitude, elevation, and the types if surface material.

The value of the gravitational field at any point is space is equal to the force

experienced by a 1-kilogram mass placed at that point.

linear momentum=mass x velocity

v

mass

Momentum uses the symbol p.

There isn't a

special

unit for momentum.

momentum unit:

kilogram-meter per second

(kg m/s)

.

momentum is a vector quantity

An object can have a large momentum

vector quantity

its magnitude is the straight-line distance between the initial and final locations of the object

its direction is from the initial location to the final location

Displacement

[The acceleration and the velocity point in opposite directions]

[The acceleration and the velocity point in same direction]

Aristotle vs. Galileo

The heavier banana will fall faster than the lighter banana!

The only reason why that happens is because air resistance slows down the lighter banana. If air resistance was reduced, they would fall at the same time!

A push or pull.

As the one-eyed minion

pushes

the other minion away, he

pulls

the banana (from the other minion's hands) towards his mouth.

Although we don't see the force, we are able to see objects behaving in a certain manner.

EXAMPLE:

In many situations there is more than one force on an object..

When two forces of equal size act along a straight line but in opposite directions, they cancel each other.

object

straight/flat surface

2 forces of equal size

Balanced or Unbalanced forces?

Static frictional force

is equal to the force you exert.

When the minion pushes with a large force, the frictional force is large.

Frictional force is small if the minion pushed with a small force.

Centripetal Acceleration

Collisions

is the force that makes a moving object change direction

is not a particular force, but the name given to the net force responsible for circular motion

acts at right angles to the velocity at any instant

is directed toward the center of a circle

When the speed of a circular motion is constant, it's called an uniform circular motion.

Centripetal Force

occurs whenever a moving object changes direction

does not change the speed of an object

acts at right angles to the velocity at any instant

is directed toward the center of a circle

In a circular motion, the velocity is tangential (lies on a tangent to the path), centripetal acceleration and centripetal force point toward the center of a circle. Centripetal acceleration and velocity are always perpendicular while centripetal force and centripetal acceleration are always parallel to each other.

Aristotle

Galileo

path traveled by ball

m

r

v

r = radius of circle

m = mass of the ball

v = speed of the ball

Centripetal force =

mv

r

2

are periodic rise and fall of sea levels, as seen in a specific location on the shore, which are caused by the gravitational forces from the Moon and Sun that attract the ocean water toward them and away from other areas in the ocean. There are two high and low tides each day. The orientation of the Moon and Sun with respect to the Earth determine when the highest and lowest tides occur, as well as when the moderate tides occur. When the Moon and the Sun are aligned, the combined gravitational pull causes the highest tides. On the other hand, the lowest tides are typically seen at locations which are 90 degrees to the alignment of the Moon and Sun.

Elastic

Inelastic

part of the kinetic energy is changed to some other form of energy in the collision

no loss of kinetic energy in the collision

both conservation of momentum and conservation of kinetic energy are observed

Before:

After:

v

v

1

2

A minion hits the eight ball, which is initially at rest, head-on with the cue ball. Both of these balls have the same mass and the velocities are equal.

Gravitational potential energy

is energy an object possesses because of its position in a gravitational field.

A decrease in one form of energy will result in an increase in another form of energy of equal magnitude.

ΔE1 = −ΔE2

The total energy of a closed system is a constant.

∑Ef = ∑Ei = constant

Energy can neither be created nor destroyed.

1 kg = 1,000 g