Two cars left a service center at 16:30. One car travelled in one direction at 75km/hr. The other car travelled in the opposite direction at 85km/hr.
a) after how long were they 600 km apart?
b) at what time were they 600 km apart?
Thanks!!!
2006-10-27 16:56:33 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
this is a rate problem so you need to keep your units straight
if the cars are traveling in opposite directions then their speeds are additive for relative speed (meaning that if one car is going 85 and the other going 75 and the direction is opposite, they are going apart at 75+85=160 km/hr
going apart at 160 km/hr then, how long will it take to get 600 km apart?
think about it, after 1 hour, they will be 160 km apart, after 2 hours, 320 km apart
rate * time = distance
160 km/hr * t = 600 km
t=600 km/160 km/hr
t=3.75 hrs
seems right,
.75 hours is .75*60= 45 minues, so 3 hours and 45 minutes after 16:30 is 20:15
make sense?
2006-10-27 17:07:45 · answer #1 · answered by enginerd 6 · 1⤊ 0⤋
They are travelling 160 km/hr apart. So 600 km / 160 kmperhr = time... a little less than 4 hrs...
Add a little less than 4 hrs to 16:30 and you get about 20:15 +/-
2006-10-28 00:00:40 · answer #2 · answered by Holden 5 · 0⤊ 0⤋
After 1hr,
Total distance travelled -> 85 + 75 = 160 km
Therefore,
600km / 160km = 3 and 3/4 hr
At 8.15pm (20:15), the two cars were 600km apart, after travelling for 3 and 3/4 hr.
2006-10-28 00:02:49 · answer #3 · answered by lee-wlcj 2 · 0⤊ 0⤋