Question

1.

A block of mass

m

= 2.00 kg is attached to a spring of force constant

k

=

575

N/m as

shown in the figure below. The block is pulled to a position

x

i

=

4.95

cm to the right of

equilibrium and released from rest.

(a) Find the speed the block has as it passes through equilibrium if the horizontal

surface is frictionless.

(b) Find the speed the block has as it passes through equilibrium (for the first time) if

the coefficient of friction between block and surface is

μ

k

= 0.350

Answer 1

When the spring goes from extreme position to equilibrium position positive work is done by the spring. We use work energy theorem to find the final speed of the block where initial speed is zero. For the second case the net work done also includes work done by friction in addition to work done by the spring.