Average speed and average velocity – problems and solutions

Solved Problems in Linear Motion – Average speed and average velocity

1. A car travels along a straight road to the east for 100 meters in 4 seconds, then go the west for 50 meters in 1 second. Determine average speed and average velocity.

Solution

Distance = 100 meters + 50 meters = 150 meters

Displacement = 100 meters – 50 meters = 50 meters, to east.

Time elapsed = 4 seconds + 1 second = 5 seconds.

Average speed = Distance / time elapsed = 150 meters / 5 seconds = 30 meters/second.

Average velocity = Displacement / time elapsed = 50 meters / 5 seconds = 10 meters/second.

2. A person walks 4 meters east in 1 second, then walks 3 meters north in 1 second. Determine average speed and average velocity.

Solution

Distance = 4 meters + 3 meters = 7 meters

Displacement = = meters, to northeast.

Time elapsed = 1 second + 1 second = 2 seconds.

Average speed = distance / time elapsed = 7 meters / 2 seconds = 3.5 meters/second

Average velocity = displacement / time elapsed = 5 meters / 2 seconds = 2.5 meters/second

3. A runner travels around rectangle track with length = 50 meters and width = 20 meters. After travels around rectangle track two times, runner back to starting point. If time elapsed = 100 seconds, determine average speed and average velocity.

Solution

Circumference of rectangle = 2(50 meters) + 2(20 meters) = 100 meters + 40 meters = 140 meters.

Travels around rectangle 2 times = 2(140 meters) = 280 meters.

Distance = 280 meter.

Displacement = 0 meter. (runner back to start point)

Average speed = distance / time elapsed = 280 meters / 100 seconds = 2.8 meters/second.

Average velocity = displacement / time elapsed = 0 / 100 seconds = 0.

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1. Distance and displacement
2. Average speed and average velocity
3. Constant velocity
4. Constant acceleration
5. Free fall motion
6. Down motion in free fall
7. Up and down motion in free fall