A conveyor belt system delivers each 10 kg crate filled with plastic dolls to the ramp at point A, such that the crate's velocity is 2.0 m/s, directed down the ramp. If the coefficient of kinetic friction between the crate and the ramp is 0.3, determine the speed at which each crate slides off the ramp at B and onto the warehouse cart.
The figure is attached below.
On the ramp the weight of the crate decomposes along the ramp and normal to the ramp (`alpha=30 deg` is the angle of the ramp)
`G_n = G*cos(alpha)`
On the axis parallel to the ramp we have
`G_p -F_f = m*a`
`G_p -mu*G_n =m*a`
`m*g*sin(alpha) -mu*m*g*cos(alpha) =m*a`
`a =g*[sin(alpha)-mu*cos(alpha)] =9.81*[sin(30) -0.3*cos(30)]=2.36 m/s^2`
Now, the length of the ramp is given in figure. The relation between acceleration, displacement and initial end final speed is (for uniform accelerated motion)
`v_B=sqrt(2^2 +2*2.36*10) =sqrt(51.2) =7.15 m/s `
Answer: the speed of crate along the ramp at point B is 7.16 m/s