Physical Science 060 Lesson 21 Guide Speed, Velocity Objectives ...

2 physci_guide21_speed_velocity.nbKey Concepts 21.1 - Compare speed and velocity• Speed is the distance divided by the time.• The equation for speed is speed ⩵ distancetime.• Velocity is the displacement divided by the time.• The equation for velocity is velocity ⩵ displacementtime. 21.2 Compare instantaneous speed and average speed.• Instantaneous speed is the speed at a certain moment in time. This speed fluctuates and is not the same as the average speed.• Average speed is the total distance divided by the total time. It includes periods of time where the speed is faster or slower, and does notreflect the speed at any one point in time. 21.3 Graph distance vs time and find the slope.• Given a set of data including distance and time, you can construct a graph and determine the slope if it is moving at a constant speed.• Example:Slope ⩵ rise 8 0 m⩵ ⩵ 8 m ⩵ 4 m run 2 0 s 2 s s 21.4 Calculate distance, velocity, and time for moving objects.• This involves using the equation in the triangle, which gives d ⩵ v t .• Example 1: Find the distance of an object moving at 200 mimifor 3 hr. d ⩵ v t ⩵ 200 3 hr ⩵ 600 mihr hr• Example 2: Find the velocity of a car that travels 300 meters in 5 seconds. v ⩵ d t⩵ 300m5 s⩵ 60 m s• Example 3: How long will it take a jet to fly 1000 miles at 400 mihr ? t ⩵ d v ⩵ 1000mi400 mihr⩵ 2.5 hr 21.5 Add velocity vectors.• Adding velocity vectors is similar to adding displacement vectors. Determine the total vertical and horizontal velocity and use thepythagorean theorem to add them mathematically.• Example: A boat goes 10 m North, and the ocean current is stead at 1 m East. Determine the resultant velocity vector and thes svelocity that boat moves in the North-East direction. 21.5 Use speed and velocity interchangeably.• Speed and velocity mean different things. Speed does not include direction. Velocity and speed have the same magnitude when an objectsmoves in a straight line. In this case, it is appropriate to use either word to describe motion.