Need help find magnitude and angle displacement please

[Darkhrse99]

Homework Statement

A wheel with a radius of 45cm travels along a horizontal floor without slipping. At time T-1 the dot P painted on the rim is at the point of contact between the wheel and the floor.At the later time T-2 the wheel has gone through one half of a revolution. What are the magnitude an angle(relative to the floor) of the displacement of P?

The Attempt at a Solution

I believe the angle is 180* and the magnitude is 90cm. A half revolution is 180* and 2times 45cm is 90cm. Is this correct?


Thanks
Jason

 

[HallsofIvy]

Magnitude and angle of displacement of what? The center of the wheel has moved straight ahead. The angle of its displacement vector is 0. And it will have moved forward a distance equal to half the circumference of the wheel, not the diameter. Do you see why?

 

[Darkhrse99]

Magnitude and angle of displacement of what? The center of the wheel has moved straight ahead. The angle of its displacement vector is 0. And it will have moved forward a distance equal to half the circumference of the wheel, not the diameter. Do you see why?

The magnitude and displacement of P At t-0, P is at the bottom and t-2 P is at the top. Sorry I left that out of the question.

 

[Jebus_Chris]

Draw a picture of the wheel at t-1 and at t-2 on the same axis. Then connect the two points and figure out the displacement+angle.