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3 years ago

Safety precautions taken while determining the melting point of naphthalene using cooling curve

1 answer:

3 0

Answer:What precaution should you take with naphthalene? Briefly explain why there is a constant-temperature plateau in the cooling curve in Figure 1 but not in Figure 2. Briefly explain why, in Figures 1 and 2, the temperature rises immediately after the first crystals appear. If you could only record a single temperature reading in a freezing point determination experiment, which temperature should you record? (This is the point that you should observe most carefully when carrying out the experiment.) Briefly explain why it is important for the beaker of water to cool slowly and for you to stir the naphthalene liquid as it cools.

Explanation:

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What does Newton's third law describe?

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Newton's third law is: For every action, there is an equal and opposite reaction.

Explanation:

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A commuter train passes a passenger platform at a constant speed of 39.6 m/s. The train horn is sounded at its characteristic fr

Licemer1 [7]

Complete Question

A commuter train passes a passenger platform at a constant speed of 39.6 m/s. The train horn is sounded at its characteristic frequency of 350 Hz.

(a)

What overall change in frequency is detected by a person on the platform as the train moves from approaching to receding

(b) What wavelength is detected by a person on the platform as the train approaches?

Answer:

$\Delta f = 81.93 \ Hz$

$\lambda_1 = 0.867 \ m$

Explanation:

From the question we are told that

The speed of the train is $v_t = 39.6 m/s$

The frequency of the train horn is $f_t = 350 \ Hz$

Generally the speed of sound has a constant values of $v_s = 343 m/s$

Now according to dopplers equation when the train(source) approaches a person on the platform(observe) then the frequency on the sound observed by the observer can be mathematically represented as

$f_1 = f * \frac{v_s}{v_s - v_t}$

substituting values

$f_1 = 350 * \frac{343 }{343-39.6}$

$f_1 = 395.7 \ Hz$

Now according to dopplers equation when the train(source) moves away from the person on the platform(observe) then the frequency on the sound observed by the observer can be mathematically represented as

$f_2 = f * \frac{v_s}{v_s +v_t}$

substituting values

$f_2 = 350 * \frac{343}{343 + 39.6}$

$f_2 = 313.77 \ Hz$

The overall change in frequency is detected by a person on the platform as the train moves from approaching to receding is mathematically evaluated as

$\Delta f = f_1 - f_2$