Due to a poorly worded question on Monday, the super smart science guys n gals were deprived of a chance to flex their brain muscles.
Therefore, here is the improved question on Forces and Physics.
The new Appledium is a new design in car, 0-60 in 12s, 20mi to the 1l, and a braking force of 4,800N. It is ultra light at just 1,200 Kg.
A careless child runs out on the road whilst the car is traveling at 40 m/s. How many seconds will it take the car to stop.
As always, lets see your working (So that none sciencey people can understand the answer better, it is solvable and gives a chance for those in the know to show off they know, and those who don't to see how it is done.
1300 today for answers.
The Appledium is a fictional car created for the purpose of this question, just to prevent anyone making fools of themselves at the dealership.
2006-08-22 21:20:25 · 13 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Some correct answers in the sea of ignorance.
As correctly pointed out by those with Right answers, the ACCELERATION power was indeed a red Herring put in to fool you; as was the Name and Fuel consumption. Since the car is trying to stop, the power of the engine bears no relevance.
What is needed is an equation that links a deccelerating body to the time; However to use any of the possibilities, we need the Decceleration Rate.
To use acceleration = change in speed / time, you would need time and rate, as we know the change is 40 m/s, so we would need another way to find one of these unknowns.
Since we have the Braking Force is 4,800 N and the mass of 1,200kg, we can use Force = mass x acceleration in a re-arranged order to tell us a = F/m, or a=4800/1200 (48/12) = 4 m/s/s
Rate is 4m/s/s, so we can now ues the a=change/time in the form t=change/rate, or 40/4 = 10 seconds.
2006-08-23 04:27:04 · update #1
Simple, yes. If you create a simple graph showing speed over time, the area under the downward slope gives distance travelled as 200 m. This gives a demonstration of why you should not walk in front of a high speed train.
Fortunately, this was a hypothetical. So, no children or cars were harmed in the making of this question.
Whilst Epidavros did give the fastest answer and showed how he did it, you must read the points by Graham_l as these are both true and go deeper into the subject. Marks for him please.
2006-08-23 04:29:20 · update #2
Douglas_z is completely wrong - the 0-60 is irrelevant information, as useful as knowing the flavour of the cheese in the bag in the trunk.
All you need to know is the speed, mass and braking force.
Deceleration = F/m = 4 m/s/s
Time to decelerate = v/a = 10 secs.
Done.
2006-08-22 21:42:55 · answer #1 · answered by Anonymous · 0⤊ 0⤋
F=ma
4800 = 1200 * a
a = 4 m/s2
a = V/t
t = V/a
t = 40/4
t = 10s
Therefore from the time the brake is applied to the time the car comes to a halt is ten seconds, assuming that the brake is immediately and continuously applied to its maximum extent, and that the car does not skid. The reaction time of the driver would need to be added to get the total time for the car to stop.
Some interesting notes: The car is breaking the speed limit (90mph). The stopping DISTANCE for the car would be 200m, which even at 90mph indicates that the car has very poor brakes. Sadly, it's likely that any child jumping on to the road in front of such a car would be killed.
2006-08-22 23:07:13 · answer #2 · answered by Graham I 6 · 2⤊ 0⤋
I find the question to be perfectly intelligible. It does contain some superfluous information as a distraction, but the meat is this: how long will it take for an object under deceleration of 4 newtons per kilogram to go from 40 meters per second to zero meters per second? One newton will accelerate a mass of one kilogram by one meter per second. So we see at once that ten seconds are required. In this time, the car will travel fifty meters. So, is the kid dead meat? Depends on where he is.
2006-08-22 21:42:58 · answer #3 · answered by Anonymous · 2⤊ 0⤋
This is STILL a poorly written question.
0-60 WHAT in 12 s????/
And why do you insist on mixing English and Metric units so freely?????
Sorry pal, you not so smart as you think. This answer cannot be determined with the information you have given. You must tell us what the units are when you say 0-60.
And that IS the correct answer. So give me my 1300 points (I presume you mean points!) right now!
2006-08-22 21:29:16 · answer #4 · answered by MrZ 6 · 0⤊ 3⤋
Yes, blah blah, well done, actually, it depends on how careless the child is. eg if the car hits it befor stopping, and dont forget to add the drivers reaction time..
2006-08-22 21:45:20 · answer #5 · answered by yeah well 5 · 0⤊ 2⤋
i have absolutely no idea and anyway what such a morbid question to put on the net at this time of the morning lol
2006-08-22 21:45:54 · answer #6 · answered by tamzin b useful today 2 · 0⤊ 2⤋
Do you wish to allow for thinking/responce time as well as actual stopping time?
2006-08-22 22:06:33 · answer #7 · answered by Anonymous · 0⤊ 2⤋
I honestly am boozlebammed!!!
Would someone write it down in plain maths and explain it to me please.
Thanks in Advance!!
2006-08-22 23:01:07 · answer #8 · answered by kookiboo 3 · 0⤊ 2⤋
I had fish for dinner last night!
2006-08-22 21:22:34 · answer #9 · answered by Les-Paul 3 · 1⤊ 3⤋
Could you repeat the question?
2006-08-22 21:33:15 · answer #10 · answered by ? 4 · 0⤊ 3⤋