truck
2007-09-05 14:26:03 · 3 answers · asked by coolguy 1 in Science & Mathematics ➔ Physics
You can imagine the two cars as travelling along a line, each with an equation giving their location along the line. Their positions change with time. Imagine the car starts at the origin, "0" km, and the truck is at the point 110 km away, and let "t" mean time.
For the car: position = 88*t+0. For the truck: position = 75*t+110. You set the two equations equal (you want the point where the positions are the same at a given time).
88*t =75*t+110. Solve this for t and you get 8.46 hours, the time the car and truck will be in the same place.
You can check your answer by plugging in 8.46 hours to the position equations. The car will be 8.46*88 = 744.5 km from the origin point; the truck will be 8.46*75+110 = 744.5km from the start.
Another simple way is to imagine the car has to travel the 110 miles, but only it's speed relative to the truck matters. Since it's 13 km/hr faster than the truck, it will take 110km /13 km/hr = 8.46 hrs. So it would take the same amount of time as it would if the truck were stopped and the car was going only 13km/hr.
2007-09-05 14:43:13 · answer #1 · answered by bagalagalaga 5 · 0⤊ 0⤋
You can do this by deductive reasoning without a formula.
Think car doing 88 and truck doing 75 that is what? How much difference in speed is that? 13 km/hr right !
So the car is going 13 Km/hr and is 110 km behind and closing in on the truck right.
You simply divide the distance by 13 because the car is going to be gaining on the truck by 13 km every hour!
110/13 = 8.46 hours to close the distance. Now you have to convert the .46 to minutes. you do this by multiplying by 60.
60 x .46 = 27 minutes and 60 x .6 =36 seconds.
putting it all together your time is going to be:
8 hr. 27 min. 36 sec.
When you run into a problem like this it is like the truck is standing still and the car is only traveling 13 km/hr.
If your question had asked how far had the truck and car travelled before the car caught up to the truck: You will have to first firnd the hours it took the car like we just did. Then you multiply that times the speed of the truck which is 75 km/hr
75 x 8.46 = 634.5 km. is how far the truck travelled before being caught by the car.
and the car would have travelled 634.5 + the 110 km it was behing the truck to start with.
634.5 + 110 = 744.5 km. is how far the car travelled before catching the truck.
2007-09-05 21:50:09 · answer #2 · answered by JUAN FRAN$$$ 7 · 0⤊ 0⤋
OK, I have this same question for my homework. The other 2 people who answered didn't take into account the fact that you're traveling at km/hr and you're 110m behind the truck. So, you need to convert meters to kilometers. So, 110m=.11km.
d=88t-.11 (car) d=75t (truck)
set them equal to each other 88t-.11=75t, solve for t and you get .00846 of an hour or 30.46seconds.
2007-09-06 17:00:30 · answer #3 · answered by nicolee779 1 · 0⤊ 0⤋