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3 years ago

Explain how attaching the key to a piece of wood could prevent the key from sinking

Physics

2 answers:

amm18123 years ago

5 0

Wood floats, whereas the key doesn’t. If you attach the 2 together than the wood would prevent the key from sinking.

Free_Kalibri [48]3 years ago

3 0

It could prevent the key from sinking because the wood would float.

It floats because it weighs less than amount of water it would have to push out of the glass if it sank. Wood, cork, and ice are all less dense than water, and they float; rocks are more dense, so they sink. A key would also be more dense causing it to sink.

Hope this helps,

Davinia.

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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

Claudia throws a baseball to her dog. Which free-body diagram shows the

chubhunter [2.5K]

Answer:

only the weight of the ball will act on the ball

Explanation: There is no contact force on the ball. Also there is no air resistance on the ball so the friction force on the ball due to air is not shown

6 0

3 years ago

What are noble gases ? Explain each example.

victus00 [196]

Answer:

18 (VIIIa) of the periodic table. The elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og)

Explanation:

6 0

3 years ago

Pls help i will give u brainliest!

Ivan

Answer: B.

Explanation:

4 0

3 years ago

Calculate the average speed of a complete round trip in which the outgoing 300 km is covered at 93 km/h , followed by a 1.0-h lu

madreJ [45]

Answer : 63 km/h

Explanation :

Outgoing distance = 300 km.

Outgoing speed = 93 km/h.

Break time = 1 h

Return distance = 300 km

Return speed = 56 km/h

Outgoing time = outgoing distance / outgoing speed

Outgoing time = 300 km / 93 km/h = 3.225806451612 h

Return time = return distance / return speed

Return time = 300 km / 56 km/h = 5.357142867142 h

Total distance =. Outgoing distance + return distance travelled

Total distance = 300 km + 300 km = 600 km

Total time = outgoing time + break time + return time

Total time = 3.225806451612 h + 1 h+ 5. 357142867142 h = 9.582949308754 h

Average speed = total distance / total time

Average speed = 600 km / 9.582949308754 h

Average speed = 62.61120462042 km/h = 63 km/h

3 0

3 years ago