Welcome to Class What are some ways that objects move?

Agenda Speed challenge Speed and Velocity Notes

Welcome to Class How can you tell when something is moving?

Agenda Speed and Velocity Notes

Motion Def. – an objects change in position relative to a reference point To observe motion you need a reference point/frame of reference – Observe an object in relation to a stationary object Describe direction of an object with a reference direction – North, south, east, west, up, down Q: What was our frame of reference for Speed Challenge?

Motion Distance measures the path taken Displacement – change in position of an object – Must be a straight line (shorter than distance) – Must be in a particular direction Q. Which should you use when calculating how much gas you will use on a trip? Q. Which does the saying, “As the crow flies” refer to?

Speed and Velocity An object is moving if it changes position against some background that stays the same Speed – how fast an object moves – Distance and time – m/s – Equal distance in equal amounts of time = constant speed

Constant Speed

Average Speed Distance traveled divided by the total time Speed = distance/timev=d/t If you run 100 m in 10 seconds what is your average speed?

Velocity Velocity is speed and direction – 2.0 m/s north – 500 m/s toward California Direction can be positive or negative

Calculating If a person runs 30 meters in 10 seconds. What is their speed? If a car travels at 150 km/h. How long would it take them to travel 350 km? If you travel 120 km north in 3 hours, what is your velocity?

Welcome to Class If you travel 120 km north in 3 hours, what is your velocity?

Agenda Finish Speed Notes Speed Lab Speed Problems

A little bit more about Velocity If you are on a bus going 15 m/s east then you are traveling 15 m/s east. While it is moving you stand up and walk down the bus’s aisle while it is moving. Q: Are you still moving the same velocity as the bus?

15 m/s east 1 m/s east 15 m/s east + 1 m/s east = 16 m/s east 1 m/s west 15 m/s east 15 m/s east + (- 1 m/s west) = 14 m/s east

Welcome to Class What is the difference between speed and velocity?

Agenda Practice Problems Quiz Speed and Velocity problems

What is the speed of a cyclist that travels 60 km in 2 hours? Agenda 1.Review Speed 2.Acceleration Outside tomorrow!

Calculating Speed 1. A boat is traveling at a speed of 36 km per hour. It has to travel a distance of 210 km. How long will it take? 2. A car takes four hours to reach its destination. The distance was 340 miles. What was its speed? 3. A car travels 300 km in six hours. What is the speed of the car? 4. What is the speed of a jet plane that flies 7200 km in 9 hours?

5. The speed of a cruise ship is 50 km/hr. How far will it travel in 14 hours? 6. The speed of a rocket is 16,000 km/hr, and it will take 66 hours to complete its mission. How far will it go?

Acceleration We know when our speed increases or decreases our velocity changes – Also when we change direction When you change velocity you are accelerating – Change in velocity is called acceleration – Acceleration includes direction as well – Units: m/s 2

Acceleration as change in direction Acceleration is a change in the direction – WHY? Acceleration is a change in velocity – Velocity is speed AND direction If you are traveling at a constant speed and are turning in a circle, are you accelerating?

Calculating Acceleration Measure velocity at different times Equation: acceleration = final velocity – initial velocity time Or a = ∆v/t

Calculating Acceleration If acceleration is small, velocity is changing slowly If acceleration is large, velocity is changing rapidly Positive acceleration means object is speeding up Negative acceleration means object is slowing down – Velocity is decreasing

Examples A skier was originally going at 20 m/s and stopped in.5 s. What is the skier’s acceleration? A flowerpot 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. What was the acceleration of the flowerpot?

More examples You accelerate your skateboard along a straight path from 0 m/s to 4.0 m/s in 2.5 s. What is your average acceleration? Find the average acceleration of a northbound subway train that slows down from 12 m/s to 9.6 m/s in.8 s.

What does ∆ stand for? Agenda 1.Review Acceleration 2.Outside – lab

Acceleration Speeding up or slowing down – a = ∆v/t If a person travels at 10 m/s and then speeds up to 15 m/s in 1.5 s, what is their acceleration? A person starts at 20 m/s and accelerates at 2 m/s 2 until they reach 40 m/s. How long did they accelerate?

A person on a sled slides down a hill at 5 m/s until they are stopped. It takes them 5 s to stop. What is their acceleration? Agenda 1.Finish Acceleration Lab a.Graphing 2.Acceleration Problems Quiz Tomorrow!

What is acceleration? Agenda 1.Quiz 2.Finish Graphing 3.Acceleration Problems

1. What is this a graph of? 2. What is happening in this graph? Agenda 1.Finish Graphing 1.Talk about graphs 2.Motion Graphs

Calculate the speed from 12 s to 18 s Agenda Go over motion graphs worksheets Acceleration Problems

Calculating Acceleration A car accelerates from a standstill to 60 m/s in 10 s. What is the acceleration? A cyclist accelerates from 5 m/s to 10 m/s in 5 s. What is the acceleration? A runner accelerates from 2 m/s to 6 m/s at a rate of 2 m/s 2. How long did it take?

A runner achieves a speed of 11 m/s after he starts. It took him 9 s to reach that speed. How long did it take? What distance did he cover? A car is going 45 m/s and slows down to 24 m/s. It takes the car 5 s to slow down. What was the cars acceleration? After a car accelerates at 5 m/s 2 for 3 seconds it’s speed is 50 m/s. What was the initial velocity?

A person on a sled starts at the top of the hill standing still. They go down the hill and reach an acceleration of 3 m/s 2. It took 5 seconds to get to the bottom of the hill. What was the final velocity at the bottom of the hill?

A person on a sled starts at the top of the hill standing still. They go down the hill and reach an acceleration of 3 m/s 2. It took 5 seconds to get to the bottom of the hill. What was their change in velocity? Agenda for Monday Oct. 25 th 1.Review Acceleration Problems (due) 2.SQ3R Laws of Motion