my friend has a physics problem..

[robfantasy]

driving along a freeway, you notice that it takes a time t to go from one mile marker to the next. When you increase your speed by 8 mi/h , the time to go one mile decreases by 10 s . What was your original speed?

how do u get this answer..

[SicChild]

I think it's a system problem.

v = d / t

so,

t = 1 (1 mile) / v
and
t - 10 = 1 / (v + 8)

isolate a variable and solve for it...

[ADL Colin]

v1 = first velocity
v2= second velocity
d1- first distance
d2 = second distance

d1 = d2 = 1
Since d = v/t

v1*t = v2*t2 = 1

Using:
v2 = v1 +8
and t2 = t = 10

(v1 + 8)(t-10) = 1
10v1 ? 8t + 80 = 0
10v1^2 + 80v1 ? 8 = 0

Using quadratic formula with a=10, b=80, c = -8

You get v1 = ~ .09878 mph which you can verify is correct by :::

In the first mile .09878 mph means you finish in 10.12 seconds. Then in the second mile you travel at 8.09875 mph which means you finish in .12 seconds

[peteinoz]

Originally posted by Colin
v1 = first velocity
v2= second velocity
d1- first distance
d2 = second distance

d1 = d2 = 1
Since d = v/t

v1*t = v2*t2 = 1

Using:
v2 = v1 +8
and t2 = t = 10

(v1 + 8)(t-10) = 1
10v1 ? 8t + 80 = 0
10v1^2 + 80v1 ? 8 = 0

Using quadratic formula with a=10, b=80, c = -8

You get v1 = ~ .09878 mph which you can verify is correct by :::

In the first mile .09878 mph means you finish in 10.12 seconds. Then in the second mile you travel at 8.09875 mph which means you finish in .12 seconds

Erhm YEah.. what "HE" said

[Holly]

Originally posted by Colin
v1 = first velocity
v2= second velocity
d1- first distance
d2 = second distance

d1 = d2 = 1
Since d = v/t

v1*t = v2*t2 = 1

Using:
v2 = v1 +8
and t2 = t = 10

(v1 + 8)(t-10) = 1
10v1 ? 8t + 80 = 0
10v1^2 + 80v1 ? 8 = 0

Using quadratic formula with a=10, b=80, c = -8

You get v1 = ~ .09878 mph which you can verify is correct by :::

In the first mile .09878 mph means you finish in 10.12 seconds. Then in the second mile you travel at 8.09875 mph which means you finish in .12 seconds

[freeadultcontent]

Thank you for reminding me I suck at all math asside from accounting.

[KDizzla]

Originally posted by freeadultcontent
Thank you for reminding me I suck at all math asside from accounting.

Math has always been a bad to me.

[Holly]

Originally posted by KDizzla
Math has always been a bad to me.

I just noticed that in the Jessica Lynch thread.

[ADL_Christy]

I knew Colin would have the answer to this!!!!

[ADL Colin]

Originally posted by ADL_Christy
I knew Colin would have the answer to this!!!!

Hey Christy! :-)

[hjnet]

Originally posted by Colin
v1 = first velocity
v2= second velocity
d1- first distance
d2 = second distance

d1 = d2 = 1
Since d = v/t

v1*t = v2*t2 = 1

Using:
v2 = v1 +8
and t2 = t = 10

(v1 + 8)(t-10) = 1
10v1 ? 8t + 80 = 0
10v1^2 + 80v1 ? 8 = 0

Using quadratic formula with a=10, b=80, c = -8

You get v1 = ~ .09878 mph which you can verify is correct by :::

In the first mile .09878 mph means you finish in 10.12 seconds. Then in the second mile you travel at 8.09875 mph which means you finish in .12 seconds

I don't wanna be the ass here, but I think you mixed up seconds and hours somewhere.

At the beginning he drove with 50mph (and needed 72 sec for 1mile), then he increased his speed to 58mph and therefore only needed 62 sec for a mile

[ADL Colin]

Originally posted by hjnet
I don't wanna be the ass here, but I think you mixed up seconds and hours somewhere.

At the beginning he drove with 50mph (and needed 72 sec for 1mile), then he increased his speed to 58mph and therefore only needed 62 sec for a mile

Haha. Oh, shit. You're right. Forgot to convert the units.