Motion Forces Describing Motion u Acceleration Acceleration n

Motion & Forces Describing Motion u Acceleration

Acceleration n vf - v i a Acceleration t the rate of change of velocity n change in speed or direction n a: v f: v i: t: acceleration final velocity initial velocity time

Acceleration, Speed and Velocity When you think of acceleration, you probably think of something speeding up. However, an object that is slowing down also is accelerating. n Acceleration also has direction, just as velocity does n

Acceleration • If the acceleration is in the same direction as the velocity, the speed increases and the acceleration is positive. Speeding up!

Acceleration n If the speed decreases, the acceleration is in the opposite direction from the velocity, and the acceleration is negative. Slowing down!

Changing Direction A change in velocity can be either a change in how fast something is moving or a change in the direction of movement. n Any time a moving object changes direction, its velocity changes and it is accelerating. n

Changing Direction n The speed of the horses in this carousel is constant, but the horses are accelerating because their direction is changing constantly.

Calculations n A roller coaster starts down a hill at 10 m/s. Three seconds later, its speed is 32 m/s. What is the roller coaster’s acceleration? GIVEN: vi = 10 m/s t=3 s vf = 32 m/s vf - v i a=? a t WORK: a = (vf - vi) ÷ t a = (32 m/s - 10 m/s) ÷ (3 s) a = 22 m/s ÷ 3 s a = 7. 3 m/s 2

skater goes from a standstill to a speed of 6. 7 m/s in 12 seconds. What is the acceleration of the skater? GIVEN: WORK: n A Calculations vi = 0 m/s t = 12 s vf = 6. 7 m/s vf - v i a=? a t a = (vf - vi) ÷ t a = (6. 7 m/s - 0 m/s) ÷ (12 s) a = 6. 7 m/s ÷ 12 s a =. 56 m/s 2

Calculations As a shuttle bus comes to a normal stop, it slows from 9. 00 m/s to 0. 00 m/s in 5. 00 s. Find the average acceleration of the bus. n GIVEN: vi = 9 m/s t=5 s vf = 0 m/s vf - vi a=? a t WORK: a = ( v f - v i) ÷ t a = (0 m/s - 9 m/s) ÷ (5 s) a = -9 m/s ÷ 5 s a = -1. 8 m/s 2

Amusement Park Acceleration Engineers use the laws of physics to design amusement park rides that are thrilling, but harmless. n The highest speeds and accelerations usually are produced on steel roller coasters. n

Independent Activity (6 grades) n n n n Mathematical problem (create and solve) 2 Grades Typed CER 1 paragraph- 2 Grades Creative Rollercoaster -2 Grades Each student will create an acceleration mathematical practice problem to create a rollercoaster for hyper kids. You must use the CER format (Question, Claim, Evidence, Reasoning) and, there are restrictions. The restrictions are: 1. Initial Velocity must go 300 m/s or less. 2. Final velocity must be 300. 3. Time is 90 seconds or less.

CER: Use this format to start your project Question: Develop a question for Hyper kids and roller coasters. n Claim: Answer your question in one sentence n Evidence: Find evidence to support your claim n Reasoning: Use a scientific principle or vocabulary to justify your evidence n