Question

. A child of mass 30 kg skates down from the top of a ramp having a constant slope of
15. The child’s speed increases from 1 1.5ms to 1 3.0ms as she reaches the
bottom of the ramp. A force of kinetic friction of magnitude 50 N opposes her
motion. Draw the appropriate force diagram and determine the length of the ramp.
Take 10ms .

Answer 1

Considering the force acting parallel to the ramp from the diagram

$30gsin(15^0)-50=30a$

where a is the acceleration of the box,

$a=0.87ms^{-2}$

To find the the length of the ramp s,

applying equation $v^2=u^2+2as \\ 13^2=11.5^2+2\times0.87\times s \\ s=21.12m$