Good Afternoon! 2/26/2016 Starter: What does it mean that a plane is traveling at 340 km/hr? Today we are going learn how to calculate using average speeds. Answers: it is traveling 340 km/hr faster than the earth or compared to the earth

Speed Now that we know all about what we are moving in reference to, let’s talk about the fact that we are moving. How do you Define Speed? Speed is a change in distance over time. How do you calculate it? s = d t

In other words miles (distance) over or per hour (time) is miles per hour (mph) the speed we are most familiar with.

A car is moving east at 90 km/hr how far away will it be in 45 minutes? What do we know? d = t = s = now we can plug in the numbers ? 45 min 90 km/hr s = d t t x s = d x t t t x s =d 0.75 hrs x 90 km = d hr =0.75 hrs 67.5 km =d We must now solve for distance, how? Multiply both sides by t The t’s cancel out and we are left with

The distance from home plate to the pitcher's mound is 18.5 m. If a pitcher can throw a ball at 38.5 m/s, how much time does it take to reach home plate?

What do we know? d = t = s = now we can plug in the numbers 18.5 m ? 38.5 m/s s = d t t x s = d x t t t x s =d We must now solve for time, how? Multiply both sides by t The t’s cancel out and we are left with now divide by s t x s = d ss The s’s cancel out t = d s = 0.48 s t = 18.5 m 38.5 m/s

Speed Problems 1.A man is shot out of a cannon at a speed of 25 m/s he is in the air for 3.65 seconds. How far away from the cannon does he land? 2.A high school athlete runs 100 m in sec. What is her speed in m/s? 3.A bullet is shot from a rifle at 720 m/s. What time is required for the bullet to strike a target that is 3240 m?