Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 25 Apr 2015, 08:35

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# The formulas above are used to compute the distance a car

Author Message
TAGS:
Eternal Intern
Joined: 07 Jun 2003
Posts: 473
Location: Lone Star State
Followers: 1

Kudos [?]: 43 [0], given: 0

The formulas above are used to compute the distance a car [#permalink]  26 Jul 2003, 14:23
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
The formulas above are used to compute the distance a car travels after the brakes are applied. If the driver of a car applied the brakes just as a traffic light turned yellow and stopped exactly 6 seconds later, what is the value of V?
Manager
Joined: 07 Jul 2003
Posts: 56
Followers: 2

Kudos [?]: 0 [0], given: 0

Please explain the answer and how you got 20. I couldnt solve the sum at all.
Manager
Joined: 22 Jul 2003
Posts: 63
Location: CA
Followers: 1

Kudos [?]: 0 [0], given: 0

The car stopped exactly 6 seconds later (after applying the brakes)

So, 6 = 2d/v [from equation (2), t = 2d / v]
=> 2d = 6v
=> d = 3v

Putting that in equation 1, we get,

3v = 3v^2 / 20 [because d = 3v^2/20 from equation (1)]
=> v = v^2 / 20
=> 20v = v^2
=> v^2 – 20v = 0
=> v(v-20) = 0

So v=0 or v=20

Velocity cannot be 0, because that would imply that the car was not moving. So, v = 20

"If the driver of a car applied the brakes just as a traffic light turned yellow" is immaterial. Because if the guy was driving at 20mph and the above equations hold true, he will stop after 6 seconds. Where he applied the brakes(after light turned yellow, red etc.) will not have an effect on the distance traveled.
Eternal Intern
Joined: 07 Jun 2003
Posts: 473
Location: Lone Star State
Followers: 1

Kudos [?]: 43 [0], given: 0

You beat me to the punch:) I was going to show Joe the soltution
_________________

Ride em cowboy

SVP
Joined: 30 Oct 2003
Posts: 1797
Location: NewJersey USA
Followers: 5

Kudos [?]: 41 [0], given: 0

1) d = 3 * v^2 /20
2) t = 2*d/v

so from 2) d = t*v/2

now t * v/2 = 3 * v^2/20
so v = 10 * t /3
if t = 6 then v = 20
Similar topics Replies Last post
Similar
Topics:
4 Two car, S and T, each traveled a distance of 50 miles. Did car S use 3 15 Dec 2014, 08:14
1 Time speed distance formula - require more clarity 1 21 Oct 2012, 11:28
1 The table above shows the distance, in kilometers, by the 8 18 Sep 2012, 02:32
When to use the formula for WOrk problems 3 05 Mar 2012, 22:11
4 A certain bank uses the formula above to approximate the ann 7 09 Oct 2007, 11:00
Display posts from previous: Sort by