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Physics Mechanics- friction

Shah 72

Member
Apr 14, 2021
193
A wooden block of mass 3.5kg is sliding up a rough slope and passes a point A with speed 20m/s. The slope is at 29 degree to the horizontal. The block comes to rest 25m up the slope. Find its speed as it passes point A on the way down.
I calculated coefficient of friction = 0.554.
U=20m/s v= 0 and s= 25m.
By using v^2= u^2+2as, I got a= -8m/s^2.
I can't calculate after this.
Pls help
 

skeeter

Well-known member
MHB Math Helper
Mar 1, 2012
935
upslope …

$a = \dfrac{0^2-20^2}{50} = -8 \, m/s^2 = -10[\sin(29)+\mu\cos(29)] \implies \mu = 0.36$

try again …