I had gotten an answer that I'm very unsure of so I would like clarification and corrections if necessary. Thank you 1.) A block is sliding along a horizontal frictionless surface at 10.3 m/s. It then slides up an incline that has friction and is tilted at 18.0 degrees. Then it slides onto another horizontal frictionless surface that is 1.50 m above the lower one traveling at 9.13 m/s. What is the coefficient of friction on the ramp? 2.) Superman need to stop Lex Luther who is driving a 1.2x10^4 kg car at 150 km/hr. If he stops the car in 2.3s, how much power did Superman use to stop the car? 3. The attempt at a solution 1.) KEi - ƩW = PEgf + KEf 1/2mv^2 - μmgcosθ = mghf + 1/2mv^2 μ = (ghf - 1/2vi^2 + 1/2vf^2)/-gcosθ(hf-hi) that was the formula I finished with(even though it can be simplified) I'm just wondering if this is right at all 2.) P= W/Δt W= Fd F= m(vi/Δt)/Δt d= VavΔt=1/2VfΔt W= (m(vi/Δt)/Δt)1/2vfΔt P= ((m(vi/Δt)1/2vfΔt)/Δt That was my final formula for that. Again, I can simplify it but this would still give the "correct" answer. Please help!!