Speed & Velocity: Using the Velocity Equation Difference Between Speed & Velocity Using the Velocity Equation Steps for Solving Science Problems

I. Speed and Velocity A.Speed is a measure of how fast an object is moving 1.Words like fast and slow describe speed but aren’t very descriptive. After all, a fast ant is nowhere as fast as a fast car mi/hr is a better way of defining speed a.This tells you how far you travel in one hour.

I. Speed and Velocity B.Velocity tells you the speed and direction of an object 1.65 mi/hr due south is a velocity because it tells you the direction of travel as well as the speed. 2.We will be using positive and negative to describe the direction a.Positive velocities are moving forward b.Negative Velocities are moving backward

Comprehension Check A.Identify each of the following as either a speed or a velocity. 1.We drove north at mi/hr. 2.Running hard, I can run 0.2 mi/min. 3.A skydiver fell at a rate of 124 mi/hr toward the ground. 4.“Kinetic energy penetrator ammunition” fired from tank guns travel at more than 1 mi/s. Velocity Speed Velocity Speed

Comprehension Check B.Describe the speed and direction of each of the objects below. 1.Shannon was running at a positive 9m/s. a.Shannon traveled 9m every second in the forward direction. 2.Kari walked at -1.5m/s through the hall. a.Kari walked 1.5m backwards every second. 3.Michael was riding in a car that was traveling -10mi/hr. a.Michael’s car was moving 10 miles backward every hour.

II. Using the Velocity Equation A.Units of Speed and Velocity 1.mi/hr, ft/s, m/s, km/h, etc 2.All follow the pattern of distance/time B.The velocity equation can be stated as C.If you know any two of the variables, you can calculate the third variable using the equation. or

III. Steps for Solving Science Problems A.Step 1: Read the problem carefully, and identify what you are asked to find. B.Step 2: Write down the information you are given. C.Step 3: Write down any equations you know that are related to the info given. D.Step 4: Pick an equation to start with and solve it for the variable you are looking for. E.Step 5: Plug in the numbers and calculate the answer.

Example 1 – Calculating Velocity A.If a car travels 309 miles in 6.8 hours, what is the speed of the car in miles per hour? v=d=t= 309mi 6.8hrs Step 1 & 2: Identify what you are looking for & write down what you know ? Step 3: Write down the velocity equation Step 4: Solve for the unknown Step 5: Plug in numbers and calculate

Example 2 – Calculating Distance A.Light travels at the astonishing rate of 11,176,943 mi/min. If it takes light an average of 8.3 minutes to reach Earth from the sun, what is the average distance, in miles, between the Earth and Sun? v=d=t= ? 8.3min 11,176,943mi/min Step 3: Write down the velocity equation Step 4: Solve for the unknown Step 5: Plug in numbers and calculate Step 1 & 2: Identify what you are looking for & write down what you know d=vt=(11,176,943mi/min)8.3min d=92,768,626 mi or 93,000,000mi

Example 3 – Calculating Time A.The muzzle velocity of a paint ball gun can reach speeds of 152 m/s. If the paintball maintains that speed, how many seconds will it take to hit a person standing 33 meters away? v=d=t= 33m ? 152m/s Step 3: Write down the velocity equation Step 4: Solve for the unknown Step 5: Plug in numbers and calculate Step 1 & 2: Identify what you are looking for & write down what you know d=vt v v