Question

Spring is compressed to a length of 20 cm by a 20 kg object on a 20 degrees inclined surface with coefficient of kinetic friction 0.30. What is the initial velocity of the object moving up the plane? The spring constant is 980 N/m

Answer 1

Given:

$x=0.2\:\rm m$

$m=20\:\rm kg$

$k=980\:\rm N/m$

The law of conservation of energy gives

$$mv^2/2=kx^2/2$$

Hence the speed of the object

$$v=\sqrt{k/m}x\\ =\sqrt{980/20}*0.2=1.4\:\rm m/s$$