Particle Falling g=1m/s^2 how much time does it take to fall?

[Jordash]

Homework Statement

A particle falls freely through a distance of 1.00 m starting from rest. Assume resume that g = 10
m/s^2.
How much time does it take to fall? (4E-1)

Homework Equations

I think a=vf-vi/t

The Attempt at a Solution

I've tried 10m/s^2=1/10m/s-0/t

And tried to solve for t

Thanks

 

[Galadirith]

Hi Jordash, from the looks of things you are not too familiar with the equations of motion for constant acceleration (often called the SUVAT equations). Here they are in one form:

$$v_f = v_i + at$$
$$s = \frac{(v_f + v_i)}{2}t$$
$$s = v_it + \frac{1}{2}at^2$$
$$s = v_ft - \frac{1}{2}at^2$$
$$v_f^2 = v_i^2 + 2as$$

where s is displacment, and for the purposes of you question you can consider that the distance traveled by the particle. So now that's all you need to solve this problem, have a real think about what you know about the particle, don't make any assumptions and only use values that you can gather from the question, I will say that you thought that the final velocity of the particle was 0.1ms^-1, now that isn't correct as it is not as simple as deviding the distance by the acceleration. Pehaps using these equations you could also work out the correct final velocity ;-)

 

[Jordash]

Ok, let me know if I'm heading in the right direction with this, I used the equation above:

s=v_it+1/2at^2

And I got to here:

1m=0+1/2*10m/s^2*t^2

1m=5m/s^2*t^2
1m/5m/s^2=t^2

So now I need to find what t = by solving for t^2=1/5 if I'm doing it right? I hope I did it right.

Which comes out to about: .45 seconds, is that right?

Sorry I don't know how to use Latex :(

Thank you very much for the excellent list and your help.

 

[Galadirith]

Hey Jordash, perfect, congrat on the answer. And that's no problem about the latex, although if you do want to post more around these forums you might like to learn a bit for simple equations, it really isn't hard to do, infact the equations you wrote are almost in latex :D

Dont feel obligated to do so, but if you would like to learn a bit of latex you could try this http://www.sitmo.com/latex/". You can code some latex or select the symbols which shows you the code, and it shows you what it looks like in real time ;-)

Oh and also this forum has a built in Latex help, if you click this symbol:

$$\sum$$

when you are in the reply/edit post screen, if brings up a list of all the latex "things" you can do :D

 

[Jordash]

Cool thank you very much for your help :D