How Does Force Affect the Time in a Domino Effect Experiment?

[whatwasthat]

Hi
I did an experiment on dominos and came up with a set up.
The set up: I placed 20 dominos one after another with a space of 3 cm in between each along a meter scale.
The domino box had mobile top which placed right next to the dominos such that when upward force is applied it would hit the dominos and starts "the domino effect" .
The string attached to the mobile top passed through two pulley systems and the other end was attached to different weights (to control the initial force applied to the dominos).
So when the weights were allowed to fall the top of the box moved forward applying the force on the dominos.
The time taken for all 20 dominos to fall was taken. I also took down all the other details such as the weight of all the dominos and also, the weight of each of the dominos.

So now I have the force applied and the time taken for the dominos to fall. I plotted a graph of force vs 1/time , which is a straight line.

But while trying to come up with the equation to relate time, velocity of the dominos for different weights and force , is where I believe I am going wrong
I did the following :
assuming that the intial speed is = 0 of the dominos

F = m (weight used)* g
momentum (p) of the dominos = (mass of the dominos)*( change in speed)
p = m'dv
F= dp/dt
F= m'dv/dt
Fdt= m'dv
But this equation does not seem correct
can you please help me out because i need to submit the lab report by wednesday

 

[Mindscrape]

I have no idea how to help you out because you didn't really say what you needed help with, but maybe this will help?

F=dp/dt
F = d(mv)/dt
F = vdm/dt + mdv/dt
your dominoes shouldn't be losing mass so the first term goes away
F = m dv/dt
F = ma

 

[whatwasthat]

yeah ... i just need some help in coming towards the equation.. so yeah it helps thanks :D