Warm Up On a snowy day off from school you decide to go sledding. As you sit on your sled at the top of a hill, you give yourself a slight push and start to move forward down the hill. Describe your motion after you start moving

Acceleration

RATE AT WHICH AN OBJECTS SPEED CHANGES. What is acceleration? When you hear the word acceleration, what do you think of? Acceleration is the: RATE AT WHICH AN OBJECTS SPEED CHANGES.

What happens if you coast your bicycle down a long hill without pedaling? You accelerate- your speed increases steadily ( by the same amount every second). On a steeper hill, your speed increases every second, but by a bigger amount.

+ and - accleration If an object is speeding up, its acceleration is positive If an object is slowing down, its acceleration is negative If you are sledding down that hill, what is your acceleration, positive or negative?

Acceleration and Direction Just like velocity, acceleration depends on direction as well. If the velocity is in the same direction as the acceleration, the speed of the object is increasing and acceleration is +. If the velocity is in a different direction than the acceleration, the object is slowing down and acceleration is -.

A change in velocity If acceleration is a change in velocity, can there be a time when an object has a constant speed , but is still accelerating? Hint: Velocity is a change in speed and/OR direction. Yes. If an object has a constant speed, but is changing DIRECTION (like a merry-go-round) The object has acceleration

If riding a bike, which hill would you accelerate faster down?

Time Speed Time Speed 0 (start) 0(start) 1 second 1 mph 2 seconds

change in velocity (m/s) Acceleration Acceleration= change in velocity (m/s) Time (s) A= v2-v1 t