# Thread: So who's good at math? ;]

1. ## So who's good at math? ;]

I need help 2. The energy, E, of an object moving horizontally is directly proportional to the speed, V, of the object. When the speed is 10 m/s the energy is 40000 Joules.
Part A: Find an equation connecting E and V.
Can anyone at least give me a hint please?  2. ## e 4,000 joules per v 1m/s 3. Duke    Join Date
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##  Originally Posted by SIGMA [1s1k] e 4,000 joules per v 1m/s

that is the right answer, and it took me barely 20 seconds to get to it 4. ##  Originally Posted by Darrenb209 that is the right answer, and it took me barely 20 seconds to get to it
I needed to find it in a direct proportion equation like this:

x=ky

k=constant btw :L

I worked out what type of formula I just dunno what it is
Last edited by RMH94; 09-30-2010 at 01:23 PM. 5. ## Wow, i just glazed over reading that post.... Ill duck lower so it can over over my head quicker next time ! 6. Earl        Join Date
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##  Originally Posted by RMH94 Can anyone at least give me a hint please? Energy (kJ) = Speed (ms) x 4

i.e k=4

you can convert to SI, as i cba, and im not doing it all for you 7. ## 2. The energy, E, of an object moving horizontally is directly proportional to the speed, V, of the object. When the speed is 10 m/s the energy is 40000 Joules.
Part A: Find an equation connecting E and V.
I know an equation that requires the knowing the distance travelled. I will assume the object moved at 10m/s for 10 seconds. thus it moves 100m.

newtons x m = joules
400newtons x 100m = 40,000 joules

400 newtons of horizontal force moving 100m = 40,000 joules of energy
40,000 joules / 10s = 4,000 watts of power output
Last edited by Rota; 09-30-2010 at 04:44 PM. 8. ## I'm not very good at math but does that mean the equation is 400N x V = 4,000E? 9. ##  Originally Posted by Richie_B I'm not very good at math but does that mean the equation is 400N x V = 4,000E?
Almost, the equation is...
N x D = E

N = newtons
D = distance in meters
E = joules

edit: I found a velocity equation

v^2 = 2E / mass
so...
10 m/s squared = 2(40,000 joules) / 800 kilograms
Last edited by Rota; 09-30-2010 at 05:16 PM. 10. ## Rota is correct.

Just kidding. I don't even understand the question. #### Posting Permissions

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