Question

The figure shows a 1.75-kg block at rest on a ramp of height . When the block is released, it slides without friction to the bottom of the ramp, and then continuesacross a surface that is frictionless except for a rough patch of width 10.0cm that has a coefficient of kinetic friction 0.650

Find h such that the block's speed after crossing the rough patch is 3.80m/s

Answer should be in meters.

Answer 1

similar one

1)The figure shows a 1.50kg block at rest on a ramp of height h. When the block is released, it slides without friction to the bottom of the ramp, and thencontinues across a surface that is frictionless except for a rough patch of width 10.0 cm that has a coefficient of kinetic friction 0.640.

Find height such that the block's speed after crossing the rough patch is 3.80 m/s.


2)The resilin in the upper leg (coxa) of a flea has a force constant of about 30 N/m, and when the flea cocks its jumping legs, the resilin in each leg isstretched by approximately 0.10 mm.

Given that the flea has a mass of 0.50 {rm mg}, and that two legs are used in a jump, estimate the maximum height a flea can attain by using the energystored in the resilin. (Assume the resilin to be an ideal spring.)




At the top of the ramp the block has a potential energy. This potential energy should be the sum of work done against friction and the kinetic energy theblock will have after the it passes the rough patch. Therefore,

potential energy = work done against friction + kinetic energy
mgh = miu*mg*length of rough patch(in meters)
+ (mv^2)/2

We can cancel the m since it is common on both sides,

we have,
gh = miu*g*length of rough patch + (v^2)/2

9.8h = 0.64*9.8*0.1 + (3.8)^2

solve for h.