 # Average velocity – problems and solutions

Average velocity – problems and solutions

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

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

1. Question: What is average velocity? Answer: Average velocity is the total displacement of an object divided by the total time taken. It’s a vector quantity and has both magnitude and direction.

2. Question: How does average velocity differ from average speed? Answer: Average speed is the total distance traveled divided by the total time taken, and it doesn’t consider direction. Average velocity, on the other hand, considers the overall displacement (change in position) and its direction.

3. Question: If a car travels 200 km north and then 200 km south in a total of 8 hours, what is its average velocity? Answer: The car returns to its starting point, so the total displacement is 0 km. Therefore, its average velocity is .

4. Question: Can average velocity be negative? Answer: Yes, average velocity can be negative, depending on the chosen reference direction. If an object moves in the opposite direction of the reference, its average velocity will be negative.