Thiết bị không phải nguồn điện:
Đáp án D
Answer:
489.19m
Explanation:
To find the minimum distance you first calculate the time in which the teacher stops:

however, the reaction of the teacher is 0.31s later, then you use
t=13.8-0.31s=13.49s
during this time the camper has traveled a distance of:
(1)
Next you calculate the distance that teacher has traveled for 13.6s:
(2)
The minimum distance between the driver and the camper will be the difference between (2) and (1):

Answer:
Explanation:
We can prove that this is a circular motion if we demonstrate that the norm of the vector is independent of time. Hence we have

but cos^2(3t)+sin^2(3t)=1. Thus we obtain

The norm is independent of t, thus, the particle describes a circular motion
Hope this helps!!