A box with an initial speed of 5 m/s5ms is moving up a ramp. The ramp has a kinetic friction coefficient of 7/2 72 and an incline of (5 pi )/12 5π12. How far along the ramp will the box go?

1 Answer
May 14, 2017

The distance is =0.68m=0.68m

Explanation:

Taking the direction up and parallel to the plane as positive ↗^++

The coefficient of kinetic friction is mu_k=F_r/Nμk=FrN

Then the net force on the object is

F=-F_r-WsinthetaF=FrWsinθ

=-F_r-mgsintheta=Frmgsinθ

=-mu_kN-mgsintheta=μkNmgsinθ

=mmu_kgcostheta-mgsintheta=mμkgcosθmgsinθ

According to Newton's Second Law

F=m*aF=ma

Where aa is the acceleration

So

ma=-mu_kgcostheta-mgsinthetama=μkgcosθmgsinθ

a=-g(mu_kcostheta+sintheta)a=g(μkcosθ+sinθ)

a=-9.8*(7/2cos(5/12pi)+sin(5/12pi))a=9.8(72cos(512π)+sin(512π))

=-18.34ms^-2=18.34ms2

The negative sign indicates a deceleration

We apply the equation of motion

v^2=u^2+2asv2=u2+2as

u=5ms^-1u=5ms1

v=0v=0

a=-18.34ms^-2a=18.34ms2

s=(v^2-u^2)/(2a)s=v2u22a

=(0-25)/(-2*18.34)=025218.34

=0.68m=0.68m