# Clocks and vectors

1. Jan 19, 2008

### chaudown

The minute hand of a wall clock measures 12 cm from its tip to the axis about which it rotates. The magnitude and angle of the displacement vector of the tip are to be determined for three time intervals. What are the (a) magnitude and (b) angle from a quarter after the hour to half past, the (c) magnitude and (d) angle for the next half hour, and the (e) magnitude and (f) angle for the hour after that? Give all angles as positive values measured counterclockwise from the +x direction (to the right, or 3 o'clock).

I thought that the answer from (a) should be the same for (c) as (a) would be the square root of .12^2+.12^2 . Apparently its not. Any help would be appreciated. Doing vectors on clocks confuses me.

2. Jan 19, 2008

### hage567

Are you drawing the vectors out?

Part (c) is asking for the next half hour. Part (a) involved a quarter hour. If the minute hand is at the six, and then goes to the 12, what is the displacement? It won't be the same as (a).