Posted by **george** on Friday, December 31, 2010 at 8:08pm.

A railroad track and a road cross at a right angle. An observer stands on the road 70 meters south of the crossing and watches an eastbound train traveling at 60 meters per second. At how many meters per second is the train moving away from the observer 4 seconds after it passes through the intersection?

- related rate problem -
**bobpursley**, Friday, December 31, 2010 at 8:33pm
Well, 4 seconds after crossing, the train has traveled 240 m. Draw your figure, lets are 60, 240, and the hypotenuse is L=sqrt (60^2+240^2)

But in general, l^2=x^2+60^2

2L*dL/dt=2x dx/dt

you are solveing for dL/dt, you know x, dx/dt, and L.

## Answer This Question

## Related Questions

- math word problem - A car is traveling on a road that is perpendicular to a ...
- College Algebra - car traveling on a road perpendicular to railroad track, car ...
- Math - you are 70 meters from train and road crossing with the train going ...
- science physics - A chicken decides to cross a road. The road is perfectly ...
- Science - a freight train must approach a road crossing at 16km/h. after ...
- physics - an auto, moving too fast on a horizontal stretch of mountain road, ...
- Physics, HELP - AN auto, moving too fast on a horizontal stretch of mountain ...
- calculus : related rates - a balloon rises at a rate of 3 meters per second from...
- Physics - A jet is circling an airport control tower at a distance of 23.0 km. ...
- PHYSICS - A car is traveling around a circular banked road without friction ...

More Related Questions