Question

Car B starts at point X and moves clockwise around a circular track at a constant rate of 2 mph. Ten hours later, Car A leaves from point X and travels counter-clockwise around the same circular track at a constant rate of 3 mph. If the radius of the track is 10 miles, for how many hours will Car B have been traveling when the cars have passed each other for the first time and put another 12 miles between them (measured around the curve of the track)?a.4pi – 1.6b.4pi + 8.4c.4pi + 10.4d.2pi – 1.6e. 2pi – 0.8

Answer 1

Answer: B(4pi+8.4)h

Explanation:

The circular track is 2.Pi.r=20pi miles

Car b travels 10hours at 2mph, so when car a starts its journey its 20 miles from point x.

Both cars need to make a sum of 20pi-20+12 miles.

As car b speed is 2mph and car a 3mph we can say car b is going to make 2/5 and car a 3/5

car b will make

2/5 (pi20-8)miles=8pi-3,2 miles

The time is x/v

(8pi-3,2)miles/2mph=4pi-1,6 h

Remember that car b started 10 h before

4pi-1,6+10=(4pi+8,4)h