Do Now : In 1911, the fastest aircraft could travel approximately 90 mph and the fastest cars could do a little more than 100 mph. One hundred years later, these numbers seem small compared to space shuttles that travel over 17,000 mph and rocket-powered cars that can break the sound barrier. Currently, one of the fastest legal stock street cars is the Hennessey Venom GT, which can reach top speeds of 260 mph. Suppose you take a trip in this vehicle for one hour. 1.Is your speed of 260 mph relative to the car? (yes/no) 2.Will you travel exactly 260 miles? 3.More than 260 miles? 4.Less than 260 miles? Explain #1-4! (And copy down your HW!)

Instantaneous Speed A car does not always move at the same speed. You can tell the speed of the car at any instant by looking at the car’s speedometer. The speed at any instant is called the instantaneous speed. 2.2 Speed

The speedometer gives readings of instantaneous speed in both mi/h and km/h. 2.2 Speed

Any combination of units for distance and time that are useful and convenient are legitimate for describing speed: miles per hour (mi/h) kilometers per hour (km/h) centimeters per day light-years per century 2.2 Speed

Average Speed In a trip by car, the car will certainly not travel at the same speed all during the trip. (You speed up, slow down, stop, go etc…) The driver cares about the average speed for the trip as a whole The average speed is the total distance covered divided by the time. 2.2 Speed

Average speed can be calculated easily ( we will practice this later in class): For example, a distance of 240 kilometers during a time of 4 hours is an average speed of 60 km/h: 2.2 Speed

If we know average speed and travel time, the distance traveled is easy to find. 2.2 Speed So, how can we solve for TOTAL DISTANCE COVERED? Using basic algebra…. Does anything CANCEL?

If we know average speed and travel time, the distance traveled is easy to find. 2.2 Speed So, if your average speed is 80 kilometers per hour on a 4-hour trip, then you cover a total distance of _________________? TRY IT! (on looseleaf, or in the margin of Ch. 2 Guided Notes…work with the people around you, 1 minute!) x

2.2 Speed x So, if your average speed is 80 kilometers per hour on a 4-hour trip, then you cover a total distance of _________? 4 h x 80 km h = 4 x80 km = 1 320km Does anything CANCEL? So we are left with… Let’s check…does km make sense if we are solving for DISTANCE?

Your First Set of Equations!!! The Δ (DELTA ) means “change in” Add the Delta to your notes!

USE ALGEBRA… Write the “distance” formula using symbols… USE ALGEBRA… Write the “time” formula using words… AND symbols!

Δt. s = d

Δt = d___ s Change in time = Total distance covered Divided by average speed

Known s= 7 m/s Δt = 150 s Unknown Formula Show All Work

Known s= 7 m/s Δt = 150 s Unknown d = ? Formula Show All Work

Known s= 7 m/s Δt = 150 s Unknown d = ? Formula d = s. Δt Show All Work

Known s= 7 m/s Δt = 150 s Unknown d = ? Formula d = s. Δt Show All Work d = s. Δt

Known s= 7 m/s Δt = 150 s Unknown d = ? Formula d = s. Δt Show All Work d = s. Δt d = 7 m s

Known s= 7 m/s Δt = 150 s Unknown d = ? Formula d = s. Δt Show All Work d = s. Δt d = 7 m. 150 s s

Known s= 7 m/s Δt = 150 s Unknown d = ? Formula d = s. Δt Show All Work d = s. Δt d = 7 m. 150 s s 1

Known s= 7 m/s Δt = 150 s Unknown d = ? Formula d = s. Δt Show All Work d = s. Δt d = 7 m. 150 s s 1 Does anything cancel?

Known s= 7 m/s Δt = 150 s Unknown d = ? Formula d = s. Δt Show All Work d = s. Δt d = 7 m. 150 s s 1 d = 7 m. 150 = 1050 m CHECK - Does meters make sense for distance?

Known s= 7 m/s Δt = 150 s Unknown d = ? Formula d = s. Δt Show All Work d = s. Δt d = 1050 m ft = ft 1 1 m

Known s= 7 m/s Δt = 150 s Unknown d = ? Formula d = s. Δt Show All Work d = s. Δt d = 7 m. 150 s ft = ft s 1 1 m

Closing Take BACK your do now Pre Assessment Now that you have LEARNED how to correctly do this… – Review – FIX any errors in a different color (see me if you need a red pen) so I can see your thought process – Questions/ comments/ concerns? Write them in the margin! – Turn back in as your exit slip – Have a great day