A box with an initial speed of 7 m/s7ms is moving up a ramp. The ramp has a kinetic friction coefficient of 1/3 13 and an incline of ( pi )/3 π3. How far along the ramp will the box go?

1 Answer
Apr 28, 2016

l=2,41 " meters"l=2,41 meters

Explanation:

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"total energy ":E_k=1/2*m*v^2" (at A)"total energy :Ek=12mv2 (at A)

"energy changed heat due to friction :" W_f=mu* m*g*cos (pi/3)*lenergy changed heat due to friction :Wf=μmgcos(π3)l

"potential energy for the point of A :"E_p=m*g*hpotential energy for the point of A :Ep=mgh

"we can write the energy conservation equation as :"we can write the energy conservation equation as :

E_k=E_p+W_fEk=Ep+Wf

1/2*m*v^2=m*g*h+mu*m*g*cos (pi/3)*l12mv2=mgh+μmgcos(π3)l

"so ;"h=l.sin (pi/3)so ;h=l.sin(π3)

1/2*cancel(m)*v^2=cancel(m)*g*l*sin(pi/3)+mu*cancel(m)*g*cos (pi/3)*l

1/2*v^2=g*l*0,87+1/3*g*0,5*l

v^2=g*l(2*0,87+(2*0,5)/3)

v=7 m/s

7^2=g*l(1,74+1/3)

49=g*l((5,22+1)/3)

49=g*l*2,07

g=9,81 m/s^2

49=9,81*l*2,07

49=20,31*l

l=2,41 " meters"