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3 years ago

you arrive at an intersection with traffic lights that arent working because of a power outage .what do you do

Physics

2 answers:

kobusy [5.1K]3 years ago

8 0

You would proceed as if the light is a stop sign.

ElenaW [278]3 years ago

6 0

Use it as a four way stop.

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A rifle bullet travels 5000 feet in 4 seconds. What is the speed of the bullet?

Juli2301 [7.4K]

This equation is quite simple, actually
5000/4 = 1250 fps, or feet per second.

7 0

3 years ago

A train whistle is heard at 300 Hz as the train approaches town. The train cuts its speed in half as it nears the station, and t

spin [16.1K]

Answer:

The speed of the train before and after slowing down is 22.12 m/s and 11.06 m/s, respectively.

Explanation:

We can calculate the speed of the train using the Doppler equation:

$f = f_{0}\frac{v + v_{o}}{v - v_{s}}$

Where:

f₀: is the emitted frequency

f: is the frequency heard by the observer

v: is the speed of the sound = 343 m/s

$v_{o}$ : is the speed of the observer = 0 (it is heard in the town)

$v_{s}$ : is the speed of the source =?

The frequency of the train before slowing down is given by:

$f_{b} = f_{0}\frac{v}{v - v_{s_{b}}}$ (1)

Now, the frequency of the train after slowing down is:

$f_{a} = f_{0}\frac{v}{v - v_{s_{a}}}$ (2)

Dividing equation (1) by (2) we have:

$\frac{f_{b}}{f_{a}} = \frac{f_{0}\frac{v}{v - v_{s_{b}}}}{f_{0}\frac{v}{v - v_{s_{a}}}}$

$\frac{f_{b}}{f_{a}} = \frac{v - v_{s_{a}}}{v - v_{s_{b}}}$ (3)

Also, we know that the speed of the train when it is slowing down is half the initial speed so:

$v_{s_{b}} = 2v_{s_{a}}$ (4)

Now, by entering equation (4) into (3) we have:

$\frac{f_{b}}{f_{a}} = \frac{v - v_{s_{a}}}{v - 2v_{s_{a}}}$

$\frac{300 Hz}{290 Hz} = \frac{343 m/s - v_{s_{a}}}{343 m/s - 2v_{s_{a}}}$

By solving the above equation for $v_{s_{a}}$ we can find the speed of the train after slowing down:

$v_{s_{a}} = 11.06 m/s$

Finally, the speed of the train before slowing down is:

$v_{s_{b}} = 11.06 m/s*2 = 22.12 m/s$

Therefore, the speed of the train before and after slowing down is 22.12 m/s and 11.06 m/s, respectively.

I hope it helps you!

7 0

3 years ago

What generates the magnetic field in a current carrying wire?

Fynjy0 [20]

The electricity causes the magnetic field. the electricity changes the magnetic waves around the wire causing the wires waves to change, creating an electro magnet

5 0

4 years ago

How much water remains unfrozen after 62.2 kJ is transferred as heat from 364 g of liquid water initially at its freezing point?

Amanda [17]

Answer:

177.213 grams

Explanation:

Given:

Total amount of water = 364 grams

Latent heat of fusion = 333 kJ/kg

Heat transferred = 62.2 kJ

The amount of water frozen = 62.2/333 = 0.186786 kg = 186.786 grams

Hence, the amount of water remained unfrozen = Total water - Amount of water frozen

the amount of water remained unfrozen = 364 grams - 186.786 grams = 177.213 grams

6 0

4 years ago

Mr. Phillips' car is parked on a steep hill with the brakes applied and the engine off. Because of the car's position, it has gr

aivan3 [116]

Answer:

The anser is b

Explanation:

4 0

3 years ago