1. Motion Word Problems

2. Speed Versus Velocity Speed describes how fast something is moving. It is a scalar quantity (does NOT indicate direction). Even though some questions may ask you to calculate the average “velocity”, if you are given the total distance traveled and the time it took, you are actually calculating the SPEED. If you are given the displacement (where you finished compared to where you started) along with the direction, then you are calculating velocity.

3. d st d vt t v a

4. You NEED to know these equations Speed = distance ÷ time distance = speed X time Time = distance ÷ speed Velocity = displacement ÷ time Displacement = velocity X time Time = displacement ÷ velocity Acceleration = velocity ÷ time Velocity = acceleration X time Time = velocity ÷ acceleration

5. Steps when solving word problems 1. Write down what you know (example: d = 10 m & t = 5 sec.) and what you need to find (example: speed = ?) 2. Write down your equation (example: speed = d ÷ t) 3. Plug in what you know (example: speed = 10m ÷ 5sec.) 4. Solve, being sure to check your significant figures, and giving the proper units (example: speed = 2 m/sec.) 5. Check your work

6. Example #1 High speed elevators can attain a speed of 7.11m/s. How much time would they need to climb 37.5m (about 10 stories)? Speed = 7.11 m/s Distance = 37.5 m Time = ? Time = distance ÷ speed Time = 37.5 m ÷ 7.11 m/s Time = 5.27 seconds

7. Example #2 A cattle train left Halifax and traveled toward Toronto. Six hours later a diesel train left traveling at 45 km/h in an effort to catch up to the cattle train. After traveling for five hours the diesel train finally caught up. What was the cattle train's average speed? Speed (diesel) = 45 km/h Time (diesel) = 5 hours Distance travelled (diesel) = ? Distance (diesel) = speed X time Distance (diesel) = 45 km/h X 5 hours Distance (diesel) = 225 km  this is the distance where the trains met Time (cattle) = 6 hours + 5 hours = 11 hours Speed (cattle) = distance / time Speed (cattle) = 225 km / 11 hours Speed (cattle) = 20 km/h