Question

Please help, I cannot seem to get the right answer for the very last part of this. The question is part B at the very bottom of exercise.  

PRACTICE IT Use the worked example above to help you solve this problem. A block with mass of 5.77 kg is attached to a horizontal spring with spring constant k = 398 N/m, as shown in the figure. The surface the block rests upon is frictionless. The block is pulled out to xi = 0.0520 m and released.

(a) Find the speed of the block at the equilibrium point. .429 Correct: Your answer is correct. m/s

(b) Find the speed when x = 0.032 m.

.3404 Correct: Your answer is correct. m/s

(c) Repeat part (a) if friction acts on the block, with coefficient μk = 0.170.

.1149 Correct: Your answer is correct. m/s

Exercise

Use the values from PRACTICE IT to help you work this exercise. Suppose the spring system in the last example starts at x = 0 and the attached object is given a kick to the right, so it has an initial speed of 0.67 m/s.

(a) What distance from the origin does the object travel before coming to rest, assuming the surface is frictionless?

.0806 Correct: Your answer is correct. m

(b) How does the answer change if the coefficient of kinetic friction is μk = 0.170? (Use the quadratic formula.) 2.7980 (Wrong) 2.717 (Wrong) Incorrect: Your answer is incorrect.

Answer 1

Concept: find the friction force on the mass. Use work energy principle where initial kinetic energy is known from the initial speed and final kinetic energy is zero because it stops finally,

***************************************************************************************************
This concludes the answers. If there is any mistake or omission, let me know immediately and I will fix it....