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# Motion

## Acceleration

### indicates any change in the velocity vector

change in direction

increase in speed

decrease in speed

simultaneous change in speed and direction

### To find it:

the change in velocity divided by the corresponding time interval

meters per second squared

net force and velocity point in opposite directions=slowing down

Net force and velocity point in same direction= speeding up

Straight-line motion= acceleration is wither same direction as velocity or in the opposite direction to the velocity

Direction

Distance

## Velocity

### Average velocity

does not reveal information about the motion during the time interval

product of the vector, the displacement, and a positive scalar, the inverse of the time interval

x-axis, represented on the graph as x(t)

### Instantaneous velocity

a vector

magnitude is the speed

direction of motion

used to calculate the displacement of the object during a very short interval

sloping portions on graphs indicate=movement

a horizontal position=position has not changed

steeper the graph=faster speed

sign of the slope indicates direction of motion, positive slope, positive slope=motion in the +x-direction, negative slope=motion in the -x-direction

## Newton's second law

### Applying to problems

Decide what objects will have Newton's second law applied to them

Identify all the external forces acting on that object

Draw a FBD to show all the forces acting on the object

Choose a coordinate system

find the net force by adding the forces as vectors

Relate the net force to acceleration

Relate the acceleration to the change in the velocity vector during a time interval of interest

## Constant net force

### equations

change of velocity is equal to the final velocity minus the initial velocity = acceleration times the change in time

refer to page 108 and 109

position

velocity

Acceleration

neglible

## Motion of projectiles

### Projectiles

objects in free fall

motion takes place in vertical plane

### Angle of elevation

angle of initial velocity above the horizontal

### Trajectory

path it takes in air

## Apparent Weight

### elevator example

upwards the weight will be great than the true weight

downwards the weight will be less than the true weight

## Air resistance

### Drag force

increases as speed increases

the larger the surface area the more air is needed to be pushed out of the way

### Terminal velocity

the acceleration is zero

### Terminal speed

the magnitude of the terminal velocity is:

depends on:, size, shape, mass

## Vectors

### Problem solving

Vectors in different direction, Subtraction: is to add its opposite, has same magnitude but opposite direction

Multiplication, multiplyig a vector by the scalar -1 reverses the vector's direction while magnitude is unaffected

Subtraction : used to find displacement

## Words of the Day

### Forestall

to predict what is ahead

### Modus operandi

"mode of operation"

### Ne Plus ultra

the most profound degree

the journey

cures

### Explore

To investigate systematically; examine

### Red Herring

something intended to divert attention from the real problem or matter at hand

### Mash-Up

combining data from more than one source into a single integrated tool

### Interval

The amount of time between two specified instants, events, or states

rise/run

### Mass

measure of its inertia

### Weight

is the magnitude of the gravitational force acting on it