A 2 kg block collides with a horizontal spring of force constant 4 N/m. The spring is compressed by 8 cm from the rest position. If the coefficient of friction is 0.5, then the velocity of block with which it collide with spring is.
a)0.7 m/s
b)0.6 m/s
c)0.9 m/s
d)1.2 m/s

Question

A 2 kg block collides with a horizontal spring of force constant 4 N/m. The spring is compressed by 8 cm from the rest position. If the coefficient of friction is 0.5, then the velocity of block with which it collide with spring is.
a)0.7 m/s
b)0.6 m/s
c)0.9 m/s
d)1.2 m/s

vincent-lyon.fr · Answer

Use energy.

ujjwal · Answer

Where am i supposed to use the co-efficient of friction? @Vincent-Lyon.Fr

vincent-lyon.fr · Answer

You will need to work out the work done by friction.

F = µN = µmg and then W = - F Δl, where Δl is compression of 8 cm.

ujjwal · Answer

should it be like this??$$\frac{1}{2}Kx^2 +\mu mg\times x=\frac{1}{2}mv^2$$It gives me an answer 0.9 m/s, which is one of the options. 
But i don't know the correct answer..

Is 0.9m/s correct?

vincent-lyon.fr · Answer

Yep! g=10N/kg yields v=0.9m/s

ujjwal · Answer

Thanks a lot @Vincent-Lyon.Fr ..