Physics chapter 2

How do you find the average speed?

Speed = distance / time

How do you convert MPH to KM

MPH divided by .6214

How do you convert Kilometers to MPH

Kilometers multiplied by .6214

How do you find the meters per second

Multiply the kilometers by 1000 and divide by 3600 since there are 3600 seconds in an hour

What is instantaneous speed?

How fast we are going at a given instant in time

the rate that distance is being covered at a given instant time

Found by using a speedometer

What is the difference between instantaneous speed and average speed?

Average speed is the average speed of the entire trip and instantaneous speed is the speed at one point in the trip

What is average speed?

The average rate at which distance is being covered

How do you find average speed?

dividing the distance traveled by the time required to cover the distance

What is velocity?

The direction and speed

If a car is going 35 MPH around a curve is the velocity constant?

No, since it is changing direction

What are the changed in velocity produced by?

Forces that act upon the car and the most important one is frictional force exerted on the tires by the roads surface

What is a vector?

Velocity is a quantity for both size and direction which are called vectors

Vector quantities include describing motion such a acceleration, velocity, force, and momentum

What is instantaneous velocity

Vector quantity have a size equal to the Instanteous speed at a given instant in time and having a direction corresponding to that of the object’s motion at that instant

What is acceleration

The rate at which velocity changes

What is average acceleration

It is found by dividing the change in velocity by the time it took o complete the change

Acceleration = change in velocity/elapsed time

What is instantaneous acceleration?

The rate at which velocity is changing at a given instant time. It is computed by finding the average acceleration does not change appreciably

How do you find the change in velocity

Subtract the initial velocity from the final velocity. To find the rate of change we need to know the time needed to produce the change.

Can a car be accelerating when its speed is constant

A car is accelerating when it is going at a constant speed around a curve because the velocity is changing and the velocity vector is changing.

What is slope

The slope indicated how rapidly the distance is changing with time at any instant in time

large upward slope means moving forward

What is negative slope

When they car travels backwards the distance from the starting point decreases, the velocity is negative

Downward slope

What is zero slope

Zero velocity, horizontal line

Steep slope

Represents a rapid change in velocity and thus a large acceleration

Can we find the distance traveled from the velocity graph?

For a constant velocity you can get the distance by multiplying the velocity by the time.

D = vt

D - distance

V - velocity

T - time

The distance traveled is equal to the area under the velocity versus time curve.

When the velocity is negative the object is traveling backward and its distance from the starting point its decreasing

What is uniform acceleration?

Unchanging accelerated motion

Occurs when there is a constant force acting on an object

Vo + (a)(t)

Vo - original velocity

A - acceleration

T - time

• Average velocity should just be half the final velocity

• If the initial velocity is zero the final velocity is acceleration x time multiplying the average velocity yields:

  D = ½ at²

• Works only if the object starts from rest

• D = Vo (t) + ½ (a)(t)²

D - is the distance the object would travel if moved with constant velocity Vo