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A 10 kg crate (begins 3m off the ground) slides along a smooth horizontal fricti

ID: 2121562 • Letter: A

Question

A 10 kg crate (begins 3m off the ground) slides along a smooth horizontal frictionless surface at a constant speed of 4 m/s. The crate then slides down a frictionless incline (that is 5m long) and across a second rough horizontal surface.


What is ther kinetic energy as it slides on the upper surface?


What is the gravitational potential energy of the crate as it slides on the upper surface with respect to the lower surface?


What is the total energy of the crate just before starting to slide down?


What is the speed of the crate when it arrives at the lower surface?


Please show work

Explanation / Answer

a)KE=0.5mv^2

=0.5*10*4*4

=80 J

b)GPE=mgh

=10*9.8*3

=294 J

c)NET energy=294+80

=374 J

4) conserving energy,

374=10*5*9.8*0.4*(4/5) + 0.5*10*v^2

or v=6.59 m/s