# HELP ME PLEASE: A flea is at point A on a horizontal turntable

1. Oct 16, 2011

### physicsnoob01

A flea is at point A on a horizontal turntable 8.1 cm from the center. The turntable is rotating at 33.9 rev/min in the counterclockwise direction. The flea jumps vertically upward to a height of 4.11 cm and lands on the turntable at point B. Place the coordinate origin at the center of the turntable with the positive x axis fixed in space and initially passing through A. The acceleration of gravity is 9.8 m/s2 .

1) Find the linear displacement of the flea.

2) Find the angle through which point A has
rotated when the flea lands.

3) Find the distance of point B from the origin
when the flea lands.

4) What angle does the radius drawn through B
make with the x-axis when the flea lands?

5) What is the linear speed of the flea after it
lands?

I am clueless as to how to get past the first part. Here was my work for part 1:
-convert 33.9 rev/min to m/s and got 0.2875 m/s
-used the equation y= a(t^2)/2 and got t= .0916 but that was only half the time, so I multipled by 2 and got time= 0.1832
-to find distance, i used d= v(t) and found the distance was 0.0527 m.

From here, I am lost. I have tried to do the arctan y/x equations to get the degrees but nothing is turning out right. And I am having difficulty understand parts 3-5 from the context of the question.

Any help is appreciated!

2. Oct 17, 2011

### rude man

What's with the arc tan? You know how long the flea was airborne, surely you can figure out how far the table has rotated in that time.

You correctly computed the velocity and airborne time of the flea, so surely you can also figure out how far it's flown?

By that time you should not have any difficulty with ## 4 & 5.