A mass vibrates back and forth from the free end of an ideal ...

[theo]

A mass vibrates back and forth from the free end of an ideal spring (k = 20. N/m) with an amplitude of 0.30 m. What is the kinetic energy of this vibrating mass when it is 0.30 m from its equilibrium position?
 
  A) 1.4 J
  B) 0.90 J
  C) zero
  D) 0.45 J
  E) It is impossible to give an answer without knowing the object's mass.

Question 2

A brass rod, 4.0 m long and with a cross sectional area of 9.2  10-6 m2 is subjected to a tension of 6.0  103 N/m2. The Young's modulus for brass is 9.0  1010 N/m2, and the Poisson ratio is 0.48. By how much does the volume of the rod change?
 
  A) 6.3  10-7 m3
  B) 0.029 m3
  C) 2.7  10-7 m3
  D) 4.0  10-7 m3
  E) 5.2  10-7 m3

[IRincones]

Answer to Question 1

C

Answer to Question 2

E

[theo]

Gracias!

[komodo7]

Excellent