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

Physical Science 060 Lesson 21 GuideSpeed, VelocityObjectives• 21.1 Compare speed and velocity.• 21.2 Compare instantaneous speed and average speed.• 21.3 Graph distance vs time and find the slope.• 21.4 Calculate distance, velocity, and time for moving objects.• 21.5 Add velocity vectors.• Language: L21.4 Recognize words that mean the same thing as speed and recognize how speed and velocity areused interchangeably at times.Key Questions (Level I IV)1. What is speed? Define it and write the equation. (I)2. What is velocity? Define it and write the equation. (I)3. How is average speed different from instantaneous speed? (I)4. Is speed or velocity a vector? Explain. (I)5. What is the speed of a car that travels 100 miles in 5 hours? (I)6. How much time would it take for a plane to fly 500 miles at 300 miles per hour? (I)7. A boat moves accross a river at 5 miles per hour. The current moves downstream at 10 miles per hour. What is the resultant (orcombined) velocity of the boat? Draw a diagram and show your caculations. (II)8. Convert 100 miles per hour to meters per second. (II)9. Use the following data to graph the distance vs time of a moving object and find the slope (or velocity). (II)Distance (m) Time (s)5 110 215 310. A car leaves at 6 PM and arrives at 2 AM. It covers a distance of 360 miles. What is the average speed of the car? (II)11. The speed of sound is 770 mi . How long does it take for thunder to travel 1 mile? (II)hr12. What is the average speed of a pedestrian who walks 8 blocks north and 7 blocks east in 30 minutes? (II)13. What is the average velocity of the same pedestrian? (II)14. A bowling ball is sent down a 20m lane. The bowler hears the bowling ball smash the pins exactly 3 seconds after they release the ball.What is the speed of the bowling ball? (*Hint - the speed of sound is 342 m s ) (III)15. Two trains approach each other from an initial distance of 100 miles. They pass each other after 1 hour and one train (A) reaches thestarting point of the other train (B) after 2.5 hours. How fast were both trains moving and where did they meet? (III)16. Graph a distance vs time graph of a ball rolling up a hill and then down a hill. Show the points at which the velocity is maximum andminimum (III)17. A spaceship moves at 40% of the speed of light. How much time will a space traveler experience compared to his counterpart on Earthwho experiences 1 yr? (IV)18. Two boats are heading away from shore. Boat 1 heads due north at a speed of 3 m/s relative to the shore. Relative to Boat 1, Boat 2 ismoving 40° north of east at a speed of 1.7 m/s. A passenger on Boat 2 walks due east across the deck at a speed of 1.1 m/s relative to Boat2. What is the speed of the passenger relative to the shore? (IV)Key Vocabularyrate, speed, velocity, acceleration, displacement, distance, vector, scalar, instantaneous speed, average speed

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.