Do you know what is the difference between the "magnitude of the displacement vector" and "the actual distance skated" (parts a and b)?
Magnitude of displacement is the straight line distance from the beginning of a path to the end of the path. What is the length of the straight line drawn from the beginning position to a point half way around the circle?
In other words, part a is the diameter of the circle, part b is the half-circumference of the circle.
For part c, she goes one full circle. She ends up where she started, so the magnitude of the displacement vector is zero. The distance is the circumference.
Exactly. Good job.
Part a: diameter = 2r Part b: half circumference = pi * r Part c: magnitude = 0; distance = circumference = 2*pi*r
For the second question you need to calculate the actual length of the path. So it is half of the circumference of the circle. Can you calculate that?
1/2 * 2 * pi * r = pi * r = 3.14 * 5 m How do you get such a large number?
The radius, r, is not squared for the circumference. It is only squared for the area.
Correct. That is the answer for part b.
Then for part c you need to do the same two things you did for parts a and b, but now for a full circle.
I get it. So for part c the answer is zero (?)
The figure above is for part c.
Part c has two parts. First, the magnitude of the distance vector is zero. Then the second part of part c is the distance traveled. That is the full circumference, so take your answer before, 15.7 m (half a circumference), and multiply it by 2.