Question

An object travels North at `4 m/s` for `5 s` and then travels South at `9 m/s` for `2 s`. What are the object's average speed and velocity?

Answer 1

Average speed = `5.42 m/s`
Average velocity = `0.28 m/s`

Explanation:

We know that average speed = total distance covered/total time taken.

So,total distance covered in this case in 7 seconds is `(4*5)+(9*2)` meters or, 38 meters,hence average speed is `38/7` `m/s` or, `5. 42 m/s`

Now,avergae velocity = total displacement/total time taken

Here,the object has gone `20`meters to north and `18` meters to south,hence displacement = `(20-18) m or 2 m` (taking towards north to be positive)

Hence average velocity is `2/7 m/s` or, `0.28 m/s`

Answer 2

velocity=`2/7m/s`
speed=`5.4m/s`

Explanation: