It Is Possible to Hear an Approaching Train Before You

question 7

Multiple Choice

It is possible to hear an approaching train before you can see it by listening to the sound wave through the track. If the elastic modulus is 2.0 × 10¹¹ N/m² and the density of steel is 7.8 × 10³ kg/m³, approximately how many times faster is the speed of sound in the track than in air? (v_air ≈ 340 m/s.)

• A) 20
• B) 5
• C) 10
• D) 15
• E) 25

---

Definitions:

QBO

QuickBooks Online, a cloud-based accounting software designed for small and medium-sized businesses.

Future Sales Revenue

The anticipated income a company expects to receive from its future sales activities.

Customer Number

A unique identifier assigned to each customer for the purpose of tracking transactions and accounts in a business's record system.

Transaction

An agreement or exchange between two parties that results in the transfer of goods or services for monetary value.