Speed and Velocity Speed and Velocity Two Similar

Speed and Velocity

Speed and Velocity – Two Similar Things Speed and velocity are often used interchangeably, but are actually two different things Speed Velocity

About Speed – the amount of distance traveled in a specific amount of time Basically, speed answers the question “how long did it take you to get there? ” Speed is a scalar quantity and is therefore based entirely off of distance instead of displacement.

Calculating Speed Based on its definition, speed can easily be calculated by the following equation Speed = (distance) / (time) -- OR -s= d/t Because distance is calculated in meters, and time is in the SI unit of seconds, the units for speed are meters per second (m/s) **For large distances over longer periods of time, we can also use kilometers per hour (km/h)

Velocity While speed is scalar, velocity is a vector Basically, velocity is speed plus direction Mathematically, speed is the absolute value of velocity (in other words, velocity can be negative, but speed cannot) ***We will regularly interchange “velocity” for “speed” (especially in acceleration problems), even though we may or may not add a directional component to our value. When this is the case, we assume that velocity continues in the positive (forward) direction. Therefore, velocity = (distance) / (time) and velocity is also measured in meters per second

The Relationship Between Speed or Velocity and Distance According to its definition, speed (and also velocity) is the distance traveled over a specific amount of time. This can also be thought of as a change in position over the change in time. For example, if I am at a position of 0 meters at time 0 seconds, and I move to a position 10 meters away in 2 seconds, my speed is equal to s = change in d / change in t = (10 m – 0 m)/(2 s – 0 s) = 5 m/s This relationship between speed (or velocity) and distance is important, and becomes even more special when distance, time, and velocity are all graphed together. You will examine this relationship in the lab. . .

Example Speed Problems 1. A car travels 70 meters in 10 seconds. What is its speed? CLICK 7 FOR m/s ANSWER 2. 2. A jogger travels 2 km at a speed of 6 km/hr. How long did it take the jogger to run 2 km? CLICK 0. 333 FOR hr or. ANSWER 20 minutes 3. An airplane flies at 300 km/hr for 4 hours. How far did the airplane fly? CLICK FOR 1200 ANSWER km 4. A train travels 10 km in 12 minutes. What is its speed in kilometers per hour? CLICK 50 FOR km/hr ANSWER

REMEMBER TO WRITE OUT 2 – 5 QUESTIONS FOR NEXT CLASS!