If a car goes around a 5 mile track at 30 mph on the first lap, how fast does the car need to go on the second lap to average 60mph for the two laps?
2006-11-20 06:58:26 · 7 answers · asked by J w 1 in Science & Mathematics ➔ Mathematics
well if the car needs to go around twice and average 60 mph then it would need to travel 120 mph total, 60*2. If it went once around at 30 mph, 120-30=90. Therefore it would have to go 90mph for the second lap.
Another way to look at it would be to use the D=RT formula for distance = rate times time. Solve it for the time meaning T=D/R so the time it would take for two laps to average 60mph would be 10miles/60mph or 1/6 of an hour, or 10 mintues. Now one lap of 5 miles at 30mph would take T=5m/30mph or 1/6 hour = 10 minutes. This leaves no time for the second lap to take place.
This is a paradoxical question. If the second lap was at 90 mph then the average would be 60mph (30mph+90mph)/2=
120mph/2=60mph.
2006-11-20 07:12:58 · answer #1 · answered by kaisermojo 2 · 0⤊ 0⤋
Not possible
10 miles at 60 mph=10 minutes
5 miles at 30 mph=10 minotes
after th 1st lap, it would take infinite speed in the 2nd to average 60 mph for 2 laps.
2006-11-20 07:51:01 · answer #2 · answered by yupchagee 7 · 0⤊ 0⤋
To average 60 mph he has to go at 90 mph the second lap.
(30 + 90)/2 = 120/2 = 60.
2006-11-20 07:01:23 · answer #3 · answered by Anonymous · 0⤊ 0⤋
The first lap is completed in 1/6 hr (5m/30mph).
To average 60 for 2 laps, 60 = 10/(T1 +T2)---> T1+T2 = 1/6 hr
But since T1 is already known to be 1/6, T2 must be zero---->V2 = 5/0 = infinity.........!
2006-11-20 07:13:04 · answer #4 · answered by Steve 7 · 0⤊ 0⤋
Oh wow! rather stable! My mile is 10 min lol! a rather good variety of the persons in my grade run 6-10 min miles! the suited speed is around 6 min. the perfect runner in my college runs 6 min miles so as that's relatively stable! OMG im jealous!
2016-12-28 06:47:36 · answer #5 · answered by Anonymous · 0⤊ 0⤋
it has to goat 90 mph
2006-11-20 07:12:59 · answer #6 · answered by raj 7 · 0⤊ 0⤋
at infinite speed
2006-11-20 07:06:24 · answer #7 · answered by Dupinder jeet kaur k 2 · 2⤊ 0⤋