Posted by **Vivi** on Wednesday, February 13, 2013 at 1:59am.

Car A traveling southward towards Point P at 45 mi/hr. Car B is traveling east away from P at 30mi/hr. AT the instant when the distance AP is 60 mi and PB is 80 mi, what is the rate of change of distance AB?

- Calculus -
**Steve**, Wednesday, February 13, 2013 at 1:04pm
We have a nice 3-4-5 triangle at the moment in question, so AB = 100

If we let x and y be the distances of the two cars (B and A) then the distance d=AB is

d^2 = x^2 + y^2

2d dd/dt = 2x dx/dt + 2y dy/dt

so, when x=80 and y=60, d=100, and we have

100 dd/dt = 80(30) + 60(-45)

dd/dt = -3

## Answer this Question

## Related Questions

- PHYSICS-URGENT HELP - A stationary police car emits a sound of frequency 1200 Hz...
- Physics - The instant a traffic light turns green a car that has been waiting at...
- CALCULUS - A gas station stands at the intersection of a north-south road and an...
- Calculus - 4. A gas station stands at the intersection of a north-south road and...
- Physics - Car A is traveling at 84 km/h while Car B is traveling at 58 km/h. ...
- Physics - Car A is traveling at 84 km/h while Car B is traveling at 58 km/h. ...
- Physics - A 1500 kg car traveling at 100 km/h west collides with a 1200 kg car ...
- Physics - At the instant the traffic light turns green, a car that has been ...
- Math - A car is going 50mi/h after 5s. The car is traveling 30mi/h about how ...
- Calculus AB - A police car is chasing a suspect. The policemen is at point y=0.6...

More Related Questions