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?