Speed, Velocity and Acceleration

speed velocity and

acceleration the goals of this video is

to to investigate what is needed to

describe motion

completely to confir and contrast speed

and velocity and to learn about

acceleration a moving train is moving at

a high speed beside this man as depicted

on the image

above an object is motion if it changes

pos position relative to a reference

point objects that we call stationary

such as a tree a sign or a building make

good reference points the passenger can

use a tree as a reference point to

decide if the train is

moving the tree makes a good reference

point because it is stationary from the

passengers point of view as you can see

from the two images there is a passenger

and the

train description of motion whether or

not an object is in

motion it depends on the reference point

you choose as you can see from the three

images we have two Sky Di and an

airlan the relative motion of the air

flame is

described the also relative motion of

the white uh of the skyd in white is

also described and the relative motion

of the sky diver in black is also

described distance when an object moves

it goes from point A to point B that is

the distance it traveled is unit of

distance is in meters distance is how

much ground an object has covered during

it motion we can just simply say that

distance is a measure of separation

between two points that is point

a and point

as you can see from the two cars

described on the

image

displacement knowing how the how far

something moves is not sufficient you

must also know in what direction the

object moved displacement in house is

how far the object is it is the object

of a ro change in

position displacement is in a straight

line as described by the right line on

the

image it is different from distance

because distance cannot be in a can be

not be in a straight

line speed speed it is a rate what does

that

mean a change over time what is the

change change in position in other words

distance the standard unit is in m/

second that is the unit of speed is in

me/ seconds

therefore we can now say that to

calculate speed an average speed is the

rate for the duration of an entire Tri

this can be

calculated ready for the

equation velocity is equal speed is

equal to distance over time and B is

equal to Velocity D is equal to distance

and T is equal to

time what units do we use for speeds

the unit is in meter per

second try the practice

problems speed calculating speed if you

know the distance an object travels in a

certain amount of time you can calculate

the speed of the object what is

instantaneous

speed instantaneous speed is the

velocity of an object at a certain time

we need to remember that speed is equals

to distance over time

therefore average speed is equal to

total distance all over total

time which is different from speed

because this is total distance while

this speed is distance while in the case

of average speed is also total time well

in the case of speed it is only time

that is considered average speed is

equal to B minus U / T where B is the

final speed U is the initial speed

speed now let's look at it velocity

speed describes only how fast something

is moving to determine Direction you

need to know the velocity velocity

includes speed of an object and the

direction of it is

motion therefore you need to know the

speed and the direction of it motion

velocity because velocity depends on

direction as well as speed the velocity

of an object can change even if the

speed of the object remains

constant the speed of this car might be

constant but it is velocity is not

constant because the direction of motion

is always changing as you can see from

the image the direction is inside CL

form and it kept

changing

velocity is a description of an object's

speed

direction as the cellb direction changes

it is velocity also changes even if it

is speed stays the same if the cellb

slows down at the same

time that it changes Direction how will

it this velocity be

changed speed versus velocity how are

speed and velocity SAR they both major

fast how fast something is moving how

are speed and velocity different

velocity includes direction of motion

and speed does not the car is moving 5 m

hour is velocity more like distance or

displacement and why displacement it is

more like displacement because it

includes

Direction now here is a graph of speed

which is distance Against Time the speed

kept increasing as you can see from the

slope and then object is

stopped and when the object is stopped

therea the object begins moving at a

different

speed the thickness of a line on a craft

is called

slope the steeper the slope is and the

greater the speed a constant slope

represents motion at constant

speed using the F shown on the graph the

rise is 400 m and the run is 2 minutes

to find the slope you divide 400 m by 2

minutes and when you divide 400 by 2 it

is going to give you 200 minutes m per

minute which

is the

slope as you can see the formula for

calculating speed is equal to distance

over time here is a solved problem what

is the speed of a sailboat that is

traveling 120 m in 60

seconds step one decide what the problem

is asking a bolt traveled 120 m in 60

seconds what is the speed of the boat

step two what is the formula to

calculate speed which is cost two speed

is distance over time now you solve the

problem which is step three to solve the

problem will now say 120 m / 60 seconds

= to speed and 120 / 60 will give us 2 m

m/ seconds now you try this problem what

is the speed of a car that is traveling

150 mil in 3 hours for this and write

your answer below in the comment

section okay now you can

continue what 50 / 3 will give you

50 therefore we have 50 m per hour which

is our answer now let's see this is the

answer

acceleration acceleration is a rate at

which velocity

changes acceleration can result from

change in speeds increase or

decrease which is retardation or

deceleration a change in Direction

back for up down left or right or

changes in both therefore we can now say

that acceleration can result from a

change in

speed again acceleration is a rate of

change of velocity when the velocity of

an object changes the object is

accelerating a change in velocity can be

either a change in how fast something is

moving or a change in the direction it

is moving acceleration occurs when an

object changes it speed it is direction

or

both

now when you think of acceleration you

probably think of something speed enough

right however an object that is slowing

down is also

accelerating acceleration also has

Direction just as V

if the

acceleration is in the same direction as

velocity as the velocity the speed

increases and the acceleration is

positive just as you can see from the

car the acceleration is moving in the

same direction as the velocity of the

car in the case if the acceleration

decreases the acceleration is in the

opposite direction from the velocity and

the acceleration is is now negative as

you can see from this image the

acceleration is in Nega is in opposite

direction and the car is moving

towards the other direction which is

opposite to the

acceleration the feature draws the ball

SP toward the B of the but it goes it is

going going going a home run before

landing the ball went through several

changes in motion It sped off in the

piter's hand and lost its speed as it

travels toward the

batter the ball stopped when it hit the

ball when it hit the B changed the

direction sped off again and eventually

slowed down most examples of motion

involve similar changes in fact rarely

does any object's motion stay the same

for very

long understanding and acceleration I

want you to answer these questions in

the comment section as the ball falls

from the God's hands how does it how

does it speed

change what happens to the speed of the

ball as it rises from the ground back to

our

hands number three at what point does

the ball have zero

velocity when it stops and has no

Direction how does the velocity of the V

change when it bounces on the

floor now go ahead and answer these

questions do you know what you can feel

acceleration if you're moving at 500 mph

East without turbulance there's no

acceleration but if the flame hits an

air fets and drops 500 ft in 2 seconds

there's a large change in acceleration

and you will feel that it does not

matter whether you sped you speed up or

slow down it is still considered a

change in

acceleration in science

acceleration refers to increasing speed

decreasing speed

or changing direction a car that begins

to move from a stoft position or speeds

off to fast another car is

accelerating a car decelerates when it

stops at a right light a water scare

decelerates when the boat stops pulling

a soft wall accelerates when it changes

direction as it as it is

hit Cala acceleration acceleration is

equal to change in velocity all over

total time or acceleration can be said

to be final speed minus initial speed

all over time as you can see final speed

is B and initial speed is U while time

is T calculating acceleration as a

roller coaster car starts down a slow it

speed is 4 m/

seconds but 3 seconds later at the

bottom it speed is 22 m/ seconds

what is it is speed it is average speed

or average

acceleration what information have you

been

given initial speed is 4 M second and

final speed isal 22 M second and the

time is 3 seconds therefore all you need

to do is to use the formula b u all

T when you use the formula B- u t or a =

B- u t you V =

22 U = 4 and T = 3 seconds therefore 22

- 4 is going to give you 18 and 18 / 3

what is it going to give us if you use

calculator you will see that 6 + 6 = 12

+ 6 = 18 therefore you have

6 m/ second

squ now this is the answer as you can

see acceleration to final speed all

minus initial speed all over time and as

you can see this is how it is

solved here is a graph of acceleration

which is speed Against Time as you can

see object accelerates objects move at a

constant speed and then the object start

decelerating downwards as you can see it

is decelerating down on the

graph I want I want you to pause the

video and solve this drop your answer in

the comment section a roller coaster

velocity Coter velocity at the top of

the hill is 10 m/ seconds 2 seconds

later it

reaches the bottom of the hill with a

velocity of 26 m/ seconds what is the

acceleration of the radical of the

Coster what is your answer let's see it

the slanted straight line on this speed

passes time graph tells you that the

cyclist is accelerating at a constant

rate the slope of a speed pass time

graph tells you the object's

acceleration predicting how would the

slope of the graph change if the cyclist

were

accelerating at a greater

rate at a lesser rate

since the slope is increasing You can

conclude that the speed is also

increasing you are

accelerating distance passes time time

graph the curved line on this distance

versus time graph tells you that the

cyclist is accelerating as you can see

from the

graph acceleration problems a roller

coaster is moving at 25 m/ seconds at

the bottom of of the Hill 3 seconds

later it reaches the bottom of the hill

moving at 10 m/

seconds what was the acceleration of the

cooster the initial speed is 25 m/

seconds the final speed is 10 m/ seconds

and time given is 3 seconds therefore 25

final speed is 10 minus 25 all/ 3 10 -

25 will give us 15 - 15 all/ 3 would

give us- 5 m/ squ therefore the roller

coaster is decelerating or it is

undergoing

retardation a car's velocity changes

from 0 m/ seconds to 30 m/s in 10

seconds calculate the acceleration the

final speed is equal 30 m/ seconds and

the initial is 0 m/ seconds while the

time is 10 seconds so in this case we

now to say we will now say final minus

initial which is 30 - 0 all over the

time which is 10

seconds in this case 30 - 0 is 30 all

over 10 will give you 30 / 10 which is 3

m per second squ squ which is the

acceleration let us look at another

problem a satellite's original velocity

is 10,000 10,000 m/ seconds after 60

seconds it is going 5,000 m/ seconds

what is the acceleration in this case we

now to say final below final speed is

equals to 5,000 and final initial speed

is 10,000 and time is 60 seconds

therefore final minus initial is going

to

be 10,000 5,000 - 10,000 all over

60 5,000 - 10,000 give us - 5000 M 60

therefore our overall answer will be

acceleration

AAL 5,000 / 60 which is sorry - 5,000 /

60 which is - 83

8333 m/

squ in this case we can conclude that

this satellite is decelerating or it is

undergoing

retardation we also look at at another

problem if a speed if a speeding train

hits the brakes and it takes the train

39 seconds to go from 54.8 m/ seconds to

12 m/ seconds what is the

acceleration now our final speed is 12

m/ seconds while the initial speed is

54.8 m/

seconds as you can see from time is 39

39 seconds therefore we now say 12 -

54.8

39 which is going to give

usus

1.97 m/ s therefore we can conclude that

this train is decelerating