Energy Talk!

Robert J asked:


an 8.7 kg block slides with an initial speed of 1.66m/s up a ramp inclined at an angle of 27.4 with the horizontal. the coefficient of kinetic frition between the block and the ramp is 0.62 . use energy conservation to find the distance the block slides before coming to rest

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One Response to “Can someone helpme out with Potential Energy and Conservation Energy question?”

1. gp4rts Says:
   November 10th, 2007 at 1:35 am

   The initial energy is 0.5*m*v². The energy used in climbing the ramp is potential energy of the elevation increase = m*g*h plus the energy of friction = Fr*L. L is the distance it travels up the ramp. Also, h/L = sinθ, so the potential energy is m*g*L*sinθ. Fr is the frictional force, which is µ*Fn, where Fn is the normal component of the weight on the ramp. Fn = m*g*cosθ, so Fr = µ*m*g*cosθ and frictional energy is µ*m*g*L*cosθ These energies added together must equal the initial kinetic energy:

   0.5*m*v² = m*g*L*sinθ + µ*m*g*L*cosθ

   solve for L:

   0.5*v² = g*L*(sinθ + µ*cosθ)

   L = 0.5*v²/[ g*(sinθ + µ*cosθ)]