Re: Physics: time for car at 69.8 kph to overtake car 69 m a
staceyrho said:
I'm having problems with what formula to us for this problem. Any suggestions?
How long does it take an automobile traveling in the left lane at 69.8 km/h to overtake (become even with) another car that is traveling in the right lane at 32.1 km/h, when the cars’ from bumpers are initially 69 m apart?
Answer in units of s.
thanks
You've already been given an excellent way to approach this problem. Here's another.
Let t = time for faster car to overtake slower car
In t hours, the faster car will travel 69.8*t km.
The slower car will travel 32.1 t km
The slower car started 69 m, or 0.069km, ahead of the faster car.
So, when the faster car overtakes the slower car,
distance for faster car = distance for slower car, + 0.069
69.8t = 32.1t + .069
Solve this for t. I get t = .00183 hours
Ok....let's check.
In 0.00183 hours, the faster car travels 0.00183 * 69.8 km, or .1274 km.
In 0.00183 hours, the slower car travels 0.00183 * 32.1 km, or .0587 km
The faster car has traveled 0.1274 - 0.0587 km further than the slower car. 0.1274 - 0.0587 = .0687 km
That rounds to .069 km, or .069 *1000 m....or 69 meters.
Since the slower car was 69 meters ahead to start with, that means that the faster car will overtake the slower car in 0.00183 hours, or 0.00183 * 60 minutes.
I hope this helps you.
