Math question help
 

11. Suppose that a 5-foot-long chandelier falls from a 35-foot ceiling and that you are 6 feet tall and standing directly under the chandelier (See figure below).

(a) How long do you have to get out of the way?
Time = ___seconds

(b) If you do not duck or get out of the way, how fast will the chandelier be traveling when it hits your head?
Speed = ___feet/second

(c) If you were only 5 feet tall, how much greater would the speed of the chandelier be when it hit your head?
Speed will be ____feet/second greater

http://www.webassign.net/userimages/...d/fig_3_17.jpg


Anyone have anyidea??

11. A: Approximately 1.54 seconds
11. B: 15.1 m/s
11. C: I don't know...

no idea if those are right...

A) The chand has 24 feet to fall before hitting you.
Since I do not know where the naught key is, I will use @ instead.

X = X@ + V@t + 1/2(a)t^2
X@ = 24
V@ = 0
a = -9.81 m/s^2 = -32.2 ft/s^2

So, when X = 0,
0 = 24 - 1/2 (32.2) (t^2)
t^2 = 48/32.2 = 1.4907
t = sqrt(1.4907) = 1.22 seconds (plus or minus, but since time is only positive...)

1.22 seconds.

B)

V = V@ + at

V@ = 0 So,

V = at

t = 1.22 from A)

V@ = (-32.2) (1.22) = -39.3 feet/second

39.3 feet/second downward

C)

There's a much easier way to do this, but I can't remember the equation... Anyhow...

X = X@ + V@t + 1/2 (a) t^2

X@ = 25 feet
V@ = 0
X = 0

0 = 25 - 1/2 (32.2) t^2

t^2 = 50/32.2 = 1.55

t = sqrt(1.55) = 1.25 seconds

V = V@ + at

V@ = 0

V = (-32.2) (1.25) = -40.25 feet/second

Since speed is a scalar and has no direction, the difference is |-40.25 - -39.3| = .95

0.95 feet/second greater

With all physics, regardless of whether or not the problem was worked correctly, there is a 20% chance that those answers are incorrect. If I cared more, I would check the answers, but... I don't care. I only do this because I enjoy it. *sigh*

Btw, this is physics, not math.

thx, only if little bit earlier. I use up all my submition

Heh, seems a little much to use the @ key as the naught. Vo looks much better than V@, not to mention much easier to read. Apparently, you don't have much MATLAB, Maple, etc. programming experience with these types of problems.

Bleh. The @ key was just the first thing that popped into my mind. I wasn't trying to think of keys that looked like naught. I was thinking of keys that were round and unused, and @ was better than * and most certainly #.

I've used MATLAB before but only once. Other than that, my programming classes have yet to hit the useful stage.

Current Program: Multiple arrays of input, one array of pointers, organizing and re-arranging data.

WOW! THAT'S NOT POINTLESS!

First I did

24=4.9*(t^2)

and solve for T for seconds... what did I do wrong there? I know the funtion is

D=V(initial)*T-(4.9*T^2)


is the funtion I remeber wrong???


Oh fuck, now I know I didn't convert Meters to Feets.... I swear to god... stupid american M system...