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!

The slope of a speed time graph would be acceleration 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….

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!!!

Convert days to seconds! 1 day=24 hours x 60 min x 60s 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 60s 1 hour 1 min V=d/t=89 m/86400 s V=.001m/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 d=60 km (1000 m) D=60000

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

a=vf-vi/t a=(14.7 m/s-0 m/s)÷1.5 s A=9.8 m/s2 down 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/s2 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/s2 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/s2. Calculate how long it takes to speed up from 24.6 m/s to 26.8 m/s.

a=vf-vi/t a=(.8 m/s - .5 m/s)÷4 a=.075 m/s2 toward the shore 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/s2 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/s2 North

3. ) Marisa’s car acclerates an average rate of 2. 6 m/s2 3.) Marisa’s car acclerates an average rate of 2.6 m/s2. 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