review av are you going up or down? are you speeding up or slowing down? what will your velocity be...
TRANSCRIPT
Review
a v
Are you going up or down?
Are you speeding up or slowing down?
What will your velocity be in 1 second?
Review
a
v
Are you going up or down?
Are you speeding up or slowing down?
What will your velocity be in 1 second?
t=0
Review
av
Are you going up or down?
Are you speeding up or slowing down?
What will your velocity be in 1 second?
t=1
Review
a v
Are you going up or down?
Are you speeding up or slowing down?
What will your velocity be in 1 second?
t=2
Review
a
v
Are you going up or down?
Are you speeding up or slowing down?
What will your velocity be in 1 second?
t=3
Review
a
v
Are you going up or down?
Are you speeding up or slowing down?
What will your velocity be in 1 second?
t=4
Review
a
v
Are you going up or down?
Are you speeding up or slowing down?
What will your velocity be in 1 second?
t=5
Reviewa
v
Are you going up or down?
Are you speeding up or slowing down?
What will your velocity be in 1 second?
t=6
Bungee Jumping
Motion 1
Motion 2
Motion 3
slowing
Motion 4
bottom
Motion 5
speeding up
Motion 6
Still rising
Motion 7
top
1
2
3
4
5
6
7
Velocity Acceleration Velocity Acceleration
bottom
Problem
A car has initial velocity +30 miles/hour. It accelerates at +2 miles/hour/s for 10 seconds. What is its final velocity?
Equation #1: vf = vi + a t
Problem:
A child slides down a constant slope on a toboggan. When the child passes her older brother, he estimates her speed at 2 m/s. When she passes her younger brother 10 seconds later, he estimates her speed at 10 m/s. Estimate how far apart her brothers are standing.
Equation #2: vf = vi + a t d = 1/2 (vi + vf) t
Short Cuts!!
Problem: A boat is cruising at 3 m/s. At time
t=0, the boat begins accelerating with a=1.6 m/s/s. How far will the boat have traveled 10 seconds later?
Which equation to use? vf = vi + at d = 1/2 (vi + vf) t
Both !!
Problem:
First: what is the boat’s velocity after 10 s?
What is the boat’s average velocity? How far did the boat travel?
A boat is cruising at 3 m/s. At time t=0, the boat begins accelerating with a=1.6 m/s/s. How far will the boat have traveled 10 seconds later?
Now: vf = vi + at d = 1/2 (vi + vf) t d = vi t + 1/2 a t 2
Problem:
What do we know? What don’t we know? What don’t we care about?
A boat is cruising at 3 m/s. At time t=0, the boat begins accelerating with a=1.6 m/s/s. How far will the boat have traveled 10 seconds later?
Problem: A plane is cruising at 50 m/s. The
plane suddenly begins accelerating with a=4m/s/s until it reaches 90 m/s. How far does it travel in this time?
What do we know? What don’t we know? What don’t we care about?
OR:
How long does it take for the plane to reach 90 m/s?
What is the average velocity? What distance is covered?
A plane is cruising at 50 m/s. The plane suddenly begins accelerating with a=4m/s/s until it reaches 90 m/s. How far does it travel in this time?
Problem: A skier, starting from rest,
accelerates down a slope at 1.6 m/s/s. How far has she gone at the end of 5.0 seconds?