Question

a child of mass 30kg skates down from the top of a ramp having a constant slope of 15degree. the childs speed increases from 1.5m/s to 3m/s as she reaches the bottom of the ramp. a force of kinetic friction of magnitude 50N opposes her motion. draw the appropriate force diagram and determine the length of the ramp. take g=10m/s²

Answer 1

Hence the value of frictional force is given 50 N

let's calculate the force along the plane=mgsin15^o = 77.6 N

acceleration down the plane = $\frac{77.6-50}{30}=0.92m/s^2$

now applying

$v^2-u^2=2aS\\3^2-1.5^2=2\times0.92\times S\\S=3.67m$