Friction at an angle verification

[warmfire540]

Hey, i just want to make sure I'm doing this right:

At the end of a factory production line, boxes start from rest and slide down a 30o ramp 5.4 m long. If the slide is to take no more than 3.3 s, what is the maximum coefficient of friction between the box and the slide?


I first found out the acceleration:
5.4=0.5a(3.3)^2
a=.99m/s^2
so i then did
mgsinTHETA-umgcosTHETA=ma (mass cancels out)
4.9-8.5u=0.99
-8.5u=-3.91
u=.46...the coefficient of friction, it seems to work..

however i still need help on my post "Tension and coefficient force revisited"
THANKS for alll ya'lls help

 

[CrazyIvan]

Hey, i just want to make sure I'm doing this right:

At the end of a factory production line, boxes start from rest and slide down a 30o ramp 5.4 m long. If the slide is to take no more than 3.3 s, what is the maximum coefficient of friction between the box and the slide?I first found out the acceleration:
5.4=0.5a(3.3)^2
a=.99m/s^2
so i then did
mgsinTHETA-umgcosTHETA=ma (mass cancels out)
4.9-8.5u=0.99
-8.5u=-3.91
u=.46...the coefficient of friction, it seems to work..

however i still need help on my post "Tension and coefficient force revisited"
THANKS for alll ya'lls help

I didn't check the numbers, but your method seems correct.