 # Linear Motion-Acceleration

## Presentation on theme: "Linear Motion-Acceleration"— Presentation transcript:

Linear Motion-Acceleration

What happens if you coast down a long hill without pedaling?
Acceleration What happens if you coast down a long hill without pedaling?

At the top of the hill you move…
Acceleration At the top of the hill you move…

Acceleration slowly

As you go down the hill, your speed…
Acceleration As you go down the hill, your speed…

Gets faster and faster! You…
Acceleration Gets faster and faster! You…

Acceleration Accelerate!

Acceleration Acceleration is the rate of change in the speed of an object. Rate of change means the ratio of the amount of change divided by how much time the change takes.

Acceleration

“The Mazda Miata can go from 0 to 60 in 10 seconds!”
Acceleration “The Mazda Miata can go from 0 to 60 in 10 seconds!” What does that mean?

Acceleration The car’s speed starts at 0 and reaches 60 mph in 10 seconds. What is the car’s acceleration?

a = ? Vf= 60m/hr Vi= 0 m/hr t = 10 sec
Acceleration a = ? Vf= 60m/hr Vi= 0 m/hr t = 10 sec

This means that the car’s speed is increasing 6 mph each second!
Acceleration This means that the car’s speed is increasing 6 mph each second!

Acceleration If you were driving and a dog ran in front of your car what would you do?

Acceleration If you slammed on your brakes and came to a stop to avoid hitting the dog, did you accelerate?

Acceleration Yes, yes you did.

Acceleration In physics, accelerate refers to any change in speed, (+) or (-), though the word decelerate is used sometimes to describe motion that is slowing down

Acceleration Acceleration is: speeding up (accelerating)
slowing down (negative acceleration or decelerating) turning (changing direction)

The acceleration of an object can be in the same direction as its velocity or in the opposite direction. Velocity increases when acceleration is in the same direction.

Acceleration Units for Acceleration Most often m/s2 Ex: 10 m/s2
this means the speed is increasing by 10 m/s every second

What are some examples of Acceleration?

Is it possible to be moving and have zero acceleration?

Yes! An object has zero acceleration if it is traveling at constant speed in one direction. Ex: cruise control in a car

An object moving with constant acceleration has a velocity that changes by the same amount every second Constant acceleration is sometimes called uniform acceleration in physics problems.

An object can have acceleration but no speed.

A plane starts at rest and ends up going 200 m/s in 10 secs
A plane starts at rest and ends up going 200 m/s in 10 secs. Calculate acceleration.

A race car starts at 400 m/s and then stops in 20 seconds
A race car starts at 400 m/s and then stops in 20 seconds. Calculate the car’s acceleration.