# Relative speed of flying bird?

1. Jan 23, 2007

### shehri

1. The problem statement, all variables and given/known data
speed of man=120m/h
angle of bird flight with ground=60 degrees.

2. Relevant equations
A man on the ground sees a bird flying at angle of 60 degrees with horizontal.He started running at 120m/hour,is able to stay directly below the bird.What's bird speed?

3. The attempt at a solution

I've vainly tried to solve it by using vectors.But I'm uncertain how it'd be solved?

Last edited: Jan 23, 2007
2. Jan 23, 2007

### greze9

draw a triangle. the base is 120 for the man. if they are moving to the right, the angle is 60 upward to the right. the tangent of that angle is tan 60 = x/120. Therefore the equation is 120 tan 60 = x = 120 radical 3. then do Pythagorean theorem to find the hypotenuse (or flight of the bird) is 240.
( if you know the way 30-60-90 triangles work, you wouldn't need all that work)

3. Jan 24, 2007

### shehri

Thanks for nice help.U've pointed me in the right direction.