Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

iPad 3:34 PM 72% Item 10 MasteringPhysics A certain spring is found not to obey

ID: 1397010 • Letter: I

Question

iPad 3:34 PM 72% Item 10 MasteringPhysics A certain spring is found not to obey Hooke's law; it exerts a restoring force F, (z) =-az-Ba2 if it is stretched or compressed, where = 60.0 N/m and -180 N/m2. The mass of the spring is negligible Part A 0 Calculate the potential energy function U(x) for this spring. Let U = 0 when x Express your answer in terms of . U(z) = 30.0x2+6.0x3 Submit Give Up All attempts used, correct answer displayed Part B An object with mass 0.900 kg on a frictionless, horizontal surface is attached to this spring, pulled a distance 1.00 m to the right (the direction) to stretch the spring, and released. What is the speed of the object when it is 0.50 m to the right of the 0 equilibrium position? m/s Submit Give Up Continue >

Explanation / Answer

Apply Initail mechanical energy = final mechaincal energy

PE1 + KE1 = PE2 + KE2

(30*x1^2 + 6*x1^3) + 0 = (30*x2^2 + 6*x2^3) + 0.5*m*V2^2

here, x1 = 1m x2 = 0.5 m

(30*1^2 + 6*1^3) = (30*0.5^2 + 6*0.5^3) + 0.6*0.9*v2^2

36 = 8.25 + 0.54*v2^2

v2 = sqrt( (36-8.25)/0.54)

= 7.17 m/s