Solve the Problem $\mathrm { D }$ Of a Sound Is Related to Its Intensity

question 289

Multiple Choice

Solve the problem.
-The decibel level $\mathrm { D }$ of a sound is related to its intensity $\mathrm { I }$ by $\mathrm { D } = 10 \log \left( \frac { \mathrm { I } } { \mathrm { I } _ { 0 } } \right)$ . If $\mathrm { I } _ { 0 }$ is $10 ^ { - 12 }$ , then what is the intensity of a noise measured at 78 decibels? Express your answer in scientific notation, rounding to three significant digits, if necessary.

• A) \(7.8 \times 10 ^ { - 10 } \mathrm { Watt } / \mathrm { m } ^ { 2 }\)
• B) \(2.44 \times 10 ^ { 15 }\) watt \(/ \mathrm { m } ^ { 2 }\)
• C) \(6.31 \times 10 ^ { - 4 }\) watt \(/ \mathrm { m } ^ { 2 }\)
• D) \(6.31 \times 10 ^ { - 5 }\) watt \(/ \mathrm { m } ^ { 2 }\)

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Definitions:

Pre-Civil War Elite

The social, political, and economic upper class in American society before the outbreak of the Civil War, often associated with slave ownership and large plantations.

Tenure Of Office Act

1867 law that required the president to obtain Senate approval to remove any official whose appointment had also required Senate approval; President Andrew Johnson’s violation of the law by firing Secretary of War Edwin Stanton led to Johnson’s impeachment.

Andrew Johnson

The 17th President of the United States, who served from 1865 to 1869, succeeding Abraham Lincoln and facing significant challenges during the Reconstruction era.

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Bringing charges against a public official; for example, the House of Representatives can impeach a president for “treason, bribery, or other high crimes and misdemeanors” by majority vote, and after the trial the Senate can remove the president by a vote of two-thirds. Two presidents, Andrew Johnson and Bill Clinton, have been impeached and tried before the Senate; neither was convicted.