1. Someone rounds a rectangle with a length of 400 m and width of 100 m, 12 times in 1 hour. What are the average velocity and the average speed?
Known :
Length of rectangle = 400 meters
Width of rectangle = 100 meters
Circumference of the rectangle = (2 x 400 meters) + (2 x 100 meters) = 800 meters + 200 meters = 1000 meters
Distance = 12 x 1000 meters = 12,000 meters = 12 kilometers
Wanted : The average velocity and the average speed
Solution :
The average velocity :
The person return to the initial velocity after rounds rectangle, hence displacement of the person is 0 and the average velocity is 0.
The average speed :
The average speed = total distance / time interval = 12 km / 1 hour = 12 km/hour
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2. The connection between the distance (d) and time interval (t) of a moving object shown in the figure below. If the distance in meter and time in second, what is the average velocity.
Solution
The average speed = distance / time interval
The average velocity = 15 meters / 6 seconds = 2.5 meters/second
3. A bird flies towards the North at 16 m/s in 5 second and then towards the East at 12 m/s in 5 seconds. What is the average velocity for 10 seconds.
Solution :
The velocity of bird towards the north : 16 meters/second = 16 meters / 1 second
After 1 second, bird moves as far as 16 meters
After 2 seconds, bird moves as far as 2 x 16 = 32 meters
After 5 seconds, bird moves as far as 5 x 16 = 80 meters
The velocity of bird towards the east : 12 meters/second = 12 meters / 1 second
After 1 second, bird moves as far as 12 meter
After 2 seconds, bird moves as far as 2 x 12 = 24 meters
After 5 seconds, bird moves as far as 5 x 12 = 60 meters
Displacement (s) :
s = √802 + 602
s = √6400 + 3600
s = √10,000
s = 100 meters
The average velocity (v) :
v = displacement / time
v = 100 meters / 10 seconds
v = 10 meters/second
