CHAPTER 11 NOTES Section 2 Acceleration AccelerationThe rate

CHAPTER 11 NOTES

Section 2: Acceleration • Acceleration-The rate at which velocity changes ▫ An object accelerates when there is a change in speed, direction, or both!

• Calculating acceleration ▫ Acceleration=final velocity-initial velocity Time ▫ The slope of a speed time graph would be acceleration Constant acceleration(steady change in velocity) =straight line

Velocity formula • Velocity=distance/time • V=d/t • Put it in the triangle…. d v t

UNITS OF VELOCITY • d= meters (m) • t= seconds (s) • v=meters/second (m/s • VELOCITY MUST ALWAYS INCLUDE A DIRECTION!!! • Use the same formula to calculate speed just don’t put a direction!!!

Metal stakes are sometimes placed in glaciers to help measure a glacier’s movement. For several days in 1936 Alaska’s Black Rapids glacier surged as swiftly as 89 meters per day. Find the velocity in m/s. • V=d/t • Convert days to seconds! • 1 day=24 hours x 60 min x 60 s • 1 hour 1 min • V=d/t=89 m/86400 s • V=. 001 m/s down the valley

YOU TRY THESE!! • 1. ) Find the velocity in m/s of a swimmer who swims 110 m toward the shore in 72 s. • 2. ) Find the velocity in m/s of a baseball thrown 38 m from third base to first base in 1. 7 s. • 3. ) Calculate the distance in meters of a cyclist would travel in 5 h with a velocity of 12 km/h to the southwest.

1. ) Find the velocity in m/s of a swimmer who swims 110 m toward the shore in 72 s. • V=d/t • V=110/72 • V=1. 5 m/s toward the shore

2. )Find the velocity in m/s of a baseball thrown 38 m from third base to first base in 1. 7 s. • V=d/t • V=38/1. 7 • V=22 m/s toward first base

3. ) Calculate the distance in meters of a cyclist would travel in 5 h with a velocity of 12 km/h to the southwest. • d=vt • d=12(5) • d=60 km (1000 m) • D=60000

ACCELERATION… • a=vf-vi/t • t=vf-vi/a • Vf=vi + at

A flower pot falls off a second story windowsill. The flowerpot starts from rest and hits the sidewalk 1. 5 s later with a velocity of 14. 7 m/s. Find the acceleration. • a=vf-vi/t • a=(14. 7 m/s-0 m/s)÷ 1. 5 s • A=9. 8 m/s 2 down

Let’s do another one… • Natalie accelerates her skateboard straight along a straight path from 0 m/s to 4 m/s in 2. 5 s. Find her acceleration. • a=vf-vi/t • a=(4 m/s-0 m/s) ÷ 2. 5 • a=1. 6 m/s 2 along her path

TRY THESE ON YOUR PAPER! • 1. ) A turtle swimming in a straight line toward shore has a speed of. 5 m/s. After 4 s it’s speed is. 8 m/s, what is the turtle’s acceleration? • 2. ) Find the acceleration a northbound train that slows down from 12 m/s to 9. 6 m/s in 8 s. • 3. ) Marisa’s car accelerates an average rate of 2. 6 m/s 2. Calculate how long it takes to speed up from 24. 6 m/s to 26. 8 m/s.

A turtle swimming in a straight line toward shore has a speed of. 5 m/s. After 4 s it’s speed is. 8 m/s, what is the turtle’s acceleration? • a=vf-vi/t • a=(. 8 m/s -. 5 m/s)÷ 4 • a=. 075 m/s 2 toward the shore

2. ) Find the acceleration a northbound train that slows down from 12 m/s to 9. 6 m/s in 8 s. • a=vf-vi/t • a=(9. 6 -12)÷ 8 • a=-. 3 m/s 2 North

3. ) Marisa’s car acclerates an average rate of 2. 6 m/s 2. Calculate how long it takes to speed up from 24. 6 m/s to 26. 8 m/s. • t=vf-vi/a • t=(26. 8 -24. 6) ÷ 2. 6 • t=. 84 s