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3 years ago

An object

Physics

1 answer:

kotegsom [21]3 years ago

4 0

Answer: G the speed and direction of the object will remain constant.

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Two trains are traveling on the same track and in the same direction. The first train, which is behind the second train, blows a

Andrews [41]

Answer:

37.545 m/s

Explanation:

f' = Actual frequency of horn = 269 Hz

f = Observed frequency of horn = 290 Hz

v = Speed of sound in air = 343 m/s

$v_0$ = Speed of second train = 13.7 m/s

$v_s$ = Speed of first train

From Doppler effect we have

$f=f'\dfrac{v-v_0}{v-v_s}\\\Rightarrow v_s=v-\dfrac{f'}{f}(v-v_0)\\\Rightarrow v_s=343-\dfrac{269}{290}(343-13.7)\\\Rightarrow v_s=37.545\ m/s$

The speed of the first train is 37.545 m/s

5 0

3 years ago

2. Which of the following is not used to calculate kinetic energy?

Komok [63]

Answer:

speed cannot be used to calculate the temperature

4 0

3 years ago

Read 2 more answers

During which time does Jamal have the greatest momentum?

Yuliya22 [10]

Answer:

Momentum Packet Answer KEY - Science Online

YOU WILL SEE THE PDF

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3 years ago

Mr. Jones's prescription calls for 1.04 tablets per day. Based on this information, how many tablets should Mr. Jones take per d

Serjik [45]

Due to the fact that no one can consume .04 of a tablet, we can round down this answer to 1. This means that Mr. Jones should take C- 1 tablet per day.

I hope I've helped! :)

7 0

3 years ago

A body which has surface area 5cm² and temperature of 727°C radiates 300J of energy in one minute. Calculate it's emissivity giv

cestrela7 [59]

<h2>Answer: 0.17</h2>

Explanation:

The Stefan-Boltzmann law establishes that a black body (an ideal body that absorbs or emits all the radiation that incides on it) "emits thermal radiation with a total hemispheric emissive power proportional to the fourth power of its temperature":

$P=\sigma A T^{4}$ (1)

Where:

$P=300J/min=5J/s=5W$ is the energy radiated by a blackbody radiator per second, per unit area (in Watts). Knowing $1W=\frac{1Joule}{second}=1\frac{J}{s}$

$\sigma=5.6703(10)^{-8}\frac{W}{m^{2} K^{4}}$ is the Stefan-Boltzmann's constant.

$A=5cm^{2}=0.0005m^{2}$ is the Surface area of the body

$T=727\°C=1000.15K$ is the effective temperature of the body (its surface absolute temperature) in Kelvin.

However, there is no ideal black body (ideal radiator) although the radiation of stars like our Sun is quite close. So, in the case of this body, we will use the Stefan-Boltzmann law for real radiator bodies:

$P=\sigma A \epsilon T^{4}$ (2)