Answer:
1)
when Juan is running at constant speed of 6 m/s and when Juan walked back to starting line at constant speed of 1 m/s
2)
Juan velocity changed to 5 m/s to North West
Juan velocity changed to 7 m/s North
3)
Juan velocity changed to 5 m/s to North West
Juan velocity changed to 7 m/s North
Explanation:
Part a)
As we know that speed is rate of change in the position
so if the position is changing with time without considering the direction then it is known as speed
so correct description for speed is
when Juan is running at constant speed of 6 m/s and when Juan walked back to starting line at constant speed of 1 m/s
Part b)
When rate of change in position is described along with the direction then it is known as velocity
so the correct description for velocity is given as
Juan velocity changed to 5 m/s to North West
Juan velocity changed to 7 m/s North
Part c)
Rate of change in velocity is known as acceleration so we need to know change in velocity and time interval to find the acceleration
so here acceleration is described as
Juan velocity changed to 5 m/s to North West
Juan velocity changed to 7 m/s North