Motion, Speed, & Velocity Chapter 10 Motion, Speed, & Velocity

OBJECTIVES Explain the relationship between motion and a frame of reference. Distinguish between distance and displacement. Relate speed to distance and time. Distinguish between speed and velocity. Solve problems involving time, distance, speed, and velocity.

While watching the following clip, think of how you might describe the movement/motion of what you see…

MOTION: an object’s change in position relative to a reference point

Frame of Reference

A B DISTANCE: measures the path taken Can be straight or curved Total amount covered SI units = meters (m) Example: 5 meters (m) A B

A B DISPLACEMENT: the change in the position of an object Always indicates a direction Always in a straight line Measures only from the starting point to the ending point Example: 5 meters to the east A B

Which line is displacement? Which line is distance? END START

Distance or displacement?

10 miles

Always a straight line

Can be a straight line or curved line

20 miles east

Always shows direction

Total amount covered

Think! Give one example of distance and one example of displacement (include units): Distance: Displacement:

Speed = Distance v = d Time t SPEED: distance traveled divided by the time during which motion occurred. Speed = Distance v = d Time t Need to measure Length & Time Can’t be negative SI unit: meters/seconds (m/s)

3 TYPES OF SPEED CONSTANT (speed not changing) Example: using cruise control AVERAGE (Total distance divided by total time) Example: the entire trip speed INSTANTANEOUS (speed at any given moment) Example: using a speedometer/radar gun Main Street PP Second Street Front Street W Route 33

VELOCITY: the speed of an object in a particular direction Must include the direction object travels Example: East, West, North, South, Up, Down, etc. Speed = Distance v = d Time t Can be negative d v t v = d/t d = v * t t = d/v

RESULTANT VELOCITY: Adding or subtracting velocities Example: Boat moving on flowing river, Person walking on airplane, etc. 7 m/s East 3 m/s East 10 m/s East 7 m/s East 3 m/s West 4 m/s East

Speed or velocity?

Can’t be negative

Includes Direction

Can be negative

M/S

Think! How are velocity and speed the same? How are they different (include units)?

Velocity Practice Problem #1 A car heading east travels 180 kilometers (km) in 2 hours. How fast is the car traveling? d = t = v = d v t

Velocity Practice Problem #2 A hockey player skating at 5 m/s during practice, skates for 10,000 seconds. How far did he skate? d = t = v = d v t

Velocity Practice Problem #3 When flying their 500 mile journey for the winter, geese fly at a speed of 25 mph. How long does it take the geese to travel south? d = t = v = d v t

Comparisons Distance & Speed Displacement & Velocity ________Direction (Scalar) ___________negative Displacement & Velocity ________Direction (Vector) ___________negative NO HAVE CAN’T BE CAN BE

GRAPHING VELOCITY/SPEED x-axis = time y-axis = displacement (or distance) slope = velocity/speed y-axis faster slope = velocity = d2 – d1 t2 – t1 d = displacement t = time slope = velocity Example for Top Line slope = velocity = 100m – 0m 60s – 0s = 100m 60s = 1.67m/s slower starting point x-axis

COMMON DISPLACEMENT/TIME GRAPH TRENDS Straight diagonal line up = constant speed away from start Straight diagonal line down = constant speed toward start Straight horizontal line = speed equals zero (stopped) Curved up = acceleration Sloped down = deceleration

Graphs for 2 Runners Which graph shows one runner starting 10 yards in front of the other runner? Which graph shows one runner ending 40 yards away from the starting point? Which graph shows both runners ending at the same place at the same time?

Graphs for 2 Runners Which graph shows both runners moving at the same velocity? Which graph shows one runner passing the other runner? Which graph shows that one runner ran a total of 30 yards while the other runner ran a total of 10 yards?

Exit Ticket: Motion- Speed/ Velocity #17-20

Exit Ticket 17. Which of the following DOES NOT indicate velocity? 20 km/h SE It is 50 KM from Logan 45 km/h toward the center of town along Main St Driving 100 km/h going from Indiana to Ohio

Exit Ticket 18. Which of the following DOES NOT require a direction? Speed Velocity Displacement Acceleration

Exit Ticket 19. To measure velocity you have to have the & the of an object. speed, velocity Speed, direction Location, direction distance, time

Exit Ticket 20. Which is an example of displacement? 50 km/h 50 km 50 km south 50 km/h south