Warm Up Describe the motion of the person. Find the velocity of the person at each interval.

Warm Up Describe the motion of the person. Stands still, moves away, stands still, moves toward Find the velocity of the person at each interval. 0 m/s , 0.4 m/s, 0 m/s, 0.25 m/s

Definition: Change in velocity Acceleration Definition: Change in velocity

Speed vs. Velocity Revisited Speed = how fast on object is moving Velocity = how fast an object is moving in a certain direction Velocity speed direction

Definition: Change in velocity Acceleration Definition: Change in velocity Can be change in speed OR direction (speed up, slow down, or change direction)

Is this ball accelerating?? Yes! Because it is changing direction!

Quick Checks What is acceleration? Acceleration can be a change in ____ or ____. Is there acceleration in these situations? Why? A car speeding from red light to red light. A car on the freeway. A pendulum A car doing donuts.

Acceleration Acceleration is not just a change in velocity, it’s how fast that change happens.

Acceleration = ∆v/t Definition: Change in velocity Acceleration Can be change in speed or direction (speed up, slow down, or change direction) Acceleration = ∆v/t

Units for Acceleration a = ∆v t a = m/s a = m/s s min a = m/s2 a = m/s/min a

Acceleration Δv = vf - vi Initial Velocity (vi) – An object’s velocity when you start measuring acceleration Final Velocity (vf) – An object’s velocity when you finish measuring acceleration Δv = vf - vi

Acceleration = ∆v/t Definition: Change in velocity Acceleration Can be change in speed or direction (speed up, slow down, or change direction) Acceleration = ∆v/t ∆v = vf – vi

Acceleration Positive acceleration = speeding up Negative acceleration = slowing down

Practice! A roller coaster’s velocity at the top of a hill is 10m/s. Two seconds later it reaches the bottom of the hill with a velocity of 26m/s. What is the acceleration of the roller coaster?

Use GUESS! G: vf = 26 m/s vi = 10 m/s t = 2 s U: acceleration E: acceleration = ∆v/ t S: a = 26m/s – 10m/s 2 s S: a = 16m/s 2s a = 8m/s/s or 8m/s2 A roller coaster’s velocity at the top of a hill is 10m/s. Two seconds later it reaches the bottom of the hill with a velocity of 26m/s. What is the acceleration of the roller coaster?

Quick Checks A car travels at 60 miles per hour around a curve. Is the car accelerating? A car travels in a straight line at 60 mi/hr. Is the car accelerating? A car goes from 0 mph to 60 mph in 6 seconds. What’s the car’s acceleration?

Let’s make it a bit harder… If a Ferrari, with an initial velocity of 10 m/s, accelerates at a rate of 50 m/s2 for 3 seconds, what would its final velocity be?

Homework Speed, Velocity, Acceleration ws

Exit Question What is the final velocity of a car that starts at 10 m/s, then accelerates at 5 m/s/s for 10 seconds? USE GUESS!! 60 m/s