What would be the truck's skidding distance?

[princesspriya]

now helpp! nooo lolzz dnt go lmao since you have the right answer i think.

 

[Snazzy]

The frictional force is dependent on the mass, the coefficient of static friction, and the acceleration due to gravity, but the deceleration of the truck isn't dependent on the mass AS YOU CAN SEE WITH THE EQUATION. If you can't see that through the cancelling of the mass on both sides of the equation, then you can't move on and your answer will be wrong just as it is right now, with your teacher telling you that it is wrong.

 

[princesspriya]

but would nt the equations be F=ma and F=2ma and that cancels out the ma leaving behind a 2?

 

[tmoan]

ya so the force doubles

 

[Snazzy]

But what is F? F is the frictional force. There are no other forces acting in the direction of motion except the frictional force as I've stated numerous times before. What is the frictional force? It is uF_n where u is the coefficient of friction. What is F_n? It is equal to mg.

Put it all together and you get -umg = ma.

 

[tmoan]

no no ur wrong f1 = ma
f2 = 2ma
f1 is not equal to f2

 

[Snazzy]

Okay, I give up. If anyone wants to take over, go ahead.

 

[princesspriya]

ok i plugged in numbers and i got that the displacement would be 2x

 

[tmoan]

ok then 2x when i said 4 x i was still thinkin acc would change

 

[princesspriya]

so its 2x?? YAYYY! i understood something finallY! awww snazzyy gives up on me :(

 

[tmoan]

and acc's time squares so..
so u got it now

 

[Snazzy]

NO, IT IS NOT 2X. THE MASS CANCELS OUT ON BOTH SIDES OF THE EQUATION.

THIS EQUATION, RIGHT HERE:

$$-\mu mg = ma$$

$$-\mu g =a$$

THE DECELERATION DOES NOT DEPEND ON THE MASS.

Does that help?

 

[princesspriya]

hmm... not really nd omg relaxxx ur typing in caps calmmm downnnnnn

 

[Snazzy]

Well then, you were destined to get this question wrong.

 

[tmoan]

wait a sec let me solve it a bit

 

[princesspriya]

http://img171.imageshack.us/my.php?image=sfsdfdffe7.jpg
thats the work