Tuesday

September 2, 2014

September 2, 2014

Posted by **angel** on Thursday, April 5, 2012 at 7:49am.

at 3pm Andy began travelling South at a rate of 4mi/hr from point A

at the same time Bill began travelling West at a rate of 5mi/hr from point B to A

both stop wlking when Bill reaches point A

What time will the distance between Bill and Andy be minimized?

- calc -
**Steve**, Thursday, April 5, 2012 at 12:03pmLet A be (0,0) and B = (9,0)

The distance d between Bill and Andy after h hours can be found using

d^2 = (4h)^2 + (9-5h)^2

= 16h^2 + 81 - 90h + 25h^2

= 41h^2 - 90h + 81

d = √(41h^2 - 90h + 81)

dd/dh = (82h - 90)/√(41h^2 - 90h + 81)

dd/dh = 0 when h = 90/82 = 1.1 hr = 1:06

3:00 + 1:06 = 4:06

**Answer this Question**

**Related Questions**

physics - Two cars leave the same point at the same time, each travelling at the...

physics - Two cars leave the same point at the same time, each travelling at the...

Trigo - Two men travelling in opposite directions at the rate 18 and 22 miles ...

Math Algebra - A quick question to check my answer. Trains A & B are travelling ...

Calculus - 1)A north south highway, intersects an east west highway, at point P...

Math - Trains a and b are travelling in the same direction on parallel tracks. ...

English - Can you please help me point out the difference between "I was ...

Physics - A policeman travelling 60 km/h spots a speeder ahead , so he ...

Physics - A policeman travelling 60 km/h spots a speeder ahead , so he ...

Physics - A policeman travelling 60 km/h spots a speeder ahead , so he ...