7. A 10-kg block on a horizontal frictionless surface is attached to a light spring (force constant = 0.80 kN/m). The block is initially at rest at its equilibrium position when a force (magnitude P =
80 N) acting parallel to the surface is applied to the block, as shown. What is the speed of the
block when it is 13 cm from its equilibrium position?
P
00000000
a.
b.
0.85 m/s
0.89 m/s
0.77 m/s
0.64 m/s
0.52 m/s
d.
e.