Physics- Chapter 3: accelerated motion

Four equations to find displacement under constant acceleration

- Vf = Vi + (a)t - Xf = Xi + 1/2(Vi+ Vf)t - Xf = Xi + (Vi)(t) + 1/2 (a)(t)^2 - Vf2= Vi2 + 2a (Xf - Xi)

When can free fall acceleration be used?

- an object is dropped - object is thrown straight up

If an object is thrown straight upward

- object slows down on way up - at max height velocity= 0 m/s - object speeds up on way down

3.3 what does yf equal if something is being dropped

0- the ground is zero and your origin

3 ways acceleration can change

1. Object speeds up 2. Object slows down- negative direction 3. Object changes direction

Velocity time graph

A graph that has velocity plotted on the y axis and time plotted on the x axis

Where can displacement be found

A velocity time graph

Formula to find acceleration

A= change in velocity/ change in time = vf- vi/ tf- ti

Explain how it is possible for an object to accelerate when the object is travelling at a constant speed

Acceleration can occur when speed is constant. A negative sign indicates that your accelerating in the negative direction because the other direction was defined as positive. The velocity changes form positive to negative when the direction of motion changes, and a change in velocity is also a change in acceleration. For this reason, acceleration can change when there is a change in the direction of motion.

- acceleration

Acceleration in a negative direction

+acceleration

Acceleration in a positive direction

Constant acceleration

Acceleration that does not change over time

What do curves on a velocity time graph indicate

Acceleration thats is changing

What is the slope of the velocity time graph

Average acceleration

The sign of acceleration shows..

Direction

What is the area under the curve on a velocity time graph

Displacement

The sign of the acceleration alone does not..

Indicate whether speeding up or slowing down

Typical units of acceleration

M/ s2

Fourth quadrant

Motion is in negative direction

First quadrant

Motion is in positive direction

Sign of accelration and direction- different

Object is slowing down

Sign of acceleration and direction - same

Object is speeding up

If an object is dropped

Object speeds up in the negative direction

How many dimensions is motion in when in free fall

One dimension

What can you not tell by a velocity time graph

Position- where the object is at any point in time

If there is no change in operation

Round at end

Formula for instantaneous acceleration

Same as average acceleration: vf-vi/ tf-ti

Instantaneous acceleration

The acceleration of an object at a particular instant of time

Describe the motion of an object if its velocity and acceleration vectors have opposite signs

The object is slowing down. When the acceleration vector is in the opposite direction from the velocity direction the object slows down. When the object's acceleration is in the oppposite direction as the velocity the speed of the object decreases

Acceleration

The rate at which the velocity of an object changes

What must you consider to determine if an object is speeding up or slowing down

The sign of acceleration and the direction of motion

What does a velocity time graph show

The velocity changes with time

Uniform motion involves moving with an

Unchanging velocity

What is the positive direction

Upward

If there is a switch in operation

Use rules for multiply and then add or subtract rules

Acceleration is a

Vector

What changes at a constant rate in constant acceleration

Velocity

Non uniform motion involves moving when

Velocity is changing

Equation for final velocity

Vf= vi + a (time interval)

If you start from rest

Vi and xi =0

When does the velocity change form positive to negative

When the direction of motion changes

what is the value of free fall acceleration

g= -9.80 m/s2

if you define upward of the positive direction, g=

g= -9.80 m/s2, gravity is pulling the object down so the direction of motion going downward is negative because you defined upward as the positive direction

who determined that all freely falling objects have the same acceleration?

galileo galilei

free fall acceleration

the acceleration of an object due to only the affect of gravity

what does the positivity or negativity of gravity depend on

the coordinate system

free fall

the motion of an object when air resistance is negligible and the motion can be considered due to the force of gravity alone