A Policeman in a Stationary Car Measures the Speed of Approaching

question 52

Multiple Choice

A policeman in a stationary car measures the speed of approaching cars by means of an ultrasonic device that emits a sound with a frequency of 41.2 kHz. A car is approaching him at a speed of 33.0 m/s. The wave is reflected by the car and interferes with the emitted sound producing beats. What is the frequency of the beats? The speed of sound in air is 330 m/s.

• A) 9.2 kHz
• B) 4.1 kHz
• C) 4.6 kHz
• D) 1.2 kHz
• E) 8.2 kHz

---

Definitions:

Arbitration Provision

A clause in a contract that requires the parties to resolve disputes through arbitration rather than litigation.

Precise Time

The exact or accurate measurement of time, often determined through standardized clocks and timing systems.

Manifestation of Assent

A term used in contract law to describe an outward expression by which one party signifies their agreement to the terms offered by another.

Conditional Acceptance

An agreement to accept an offer or proposal based on the fulfillment of certain conditions.