A box with an initial speed of 7 m/s7ms is moving up a ramp. The ramp has a kinetic friction coefficient of 8/5 85 and an incline of pi /8 π8. How far along the ramp will the box go?

1 Answer
Mar 20, 2018

The distance is =1.34m=1.34m

Explanation:

Resolving in 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 of Motion

F=m*aF=ma

Where aa is the of the box

So

ma=-mu_kgcostheta-mgsinthetama=μkgcosθmgsinθ

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

The coefficient of kinetic friction is mu_k=8/5μk=85

The acceleration due to gravity is g=9.8ms^-2g=9.8ms2

The incline of the ramp is theta=1/8piθ=18π

The acceleration is a=-9.8*(8/5cos(1/8pi)+sin(1/8pi))a=9.8(85cos(18π)+sin(18π))

=-18.24ms^-2=18.24ms2

The negative sign indicates a deceleration

Apply the equation of motion

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

The initial velocity is u=7ms^-1u=7ms1

The final velocity is v=0v=0

The acceleration is a=-18.24ms^-2a=18.24ms2

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

=(0-49)/(-2*18.24)=049218.24

=1.34m=1.34m