- #1
mybrohshi5
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Homework Statement
A box of mass 11.3 kg rests on the flat bed of a truck; the box is not tied down in any way. The coefficients of friction between the box and the flat bed are mu_s = 0.19 and mu_k = 0.14. The truck stops at a stop sign and then starts to move with a carelessly large acceleration of 2.20 m/s^2.
I found the force of friction first --- 15.5 N
then i found the accel of the box --- 1.37 m/s^2
Now i am having trouble finding this next part.
If the box is a distance 1.83 m from the rear of the truck when the truck starts, how much time elapses before the box falls off the truck?
Homework Equations
f=ma
vf2=vi2+2ad
v=d/t
The Attempt at a Solution
So for this last part this is what i did.
vf22= 0 + 2(1.37)(1.83)
vf= 2.24
t = 1.83/2.24
t= 0.817 seconds
this was wrong so i thought oh well the truck is accelerating right and the box is accelerating in the opposite direction so i took a new approach.
vf22= 0 + 2(2.2-1.37)(1.83)
vf= 1.74
t = 1.83/1.74
t= 1.05 seconds
but to no avail. this was wrong also so i thought again well the truck is accelerating right and the box is accelerating left so maybe i use total acceleration
vf22= 0 + 2(2.2+1.37)(1.83)
vf= 3.61
t = 1.83/3.61
t= 0.507 seconds
wrong as well :(
i don't know what else to try.
what am i doing wrong?