A Physics Student Is Asked to Determine the Length of a Long

Multiple Choice

A physics student is asked to determine the length of a long, slender, copper bar by measuring the time required for a sound pulse to travel the length of the bar. The Young's modulus of copper is 1.1 × 10¹¹ N/m²; and its density is 8890 kg/m³. The student finds that the time for the pulse to travel from one end to the other is 5.6 × 10^-4 s. How long is the rod?

A) 11 m
B) 7.8 m
C) 5.5 m
D) 2.0 m
E) 0.45 m