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o-na [289]
3 years ago
7

In old times, before there were train signals, people who worked on the railroad would often put their ear down to the train tra

ck to listen for an oncoming train. Why would this result in hearing the train further off than just listening for the train through the air? Question 3 options: Sound travels slower in air because there are often trees and other items blocking the sound. People did not do this because sound travels faster through less dense material, like air, rather than more dense materiel, like train tracks. Sound travels slower, but louder through solid material because it is more dense, so the train could be heard better this way. Sound waves travel faster in more dense material, and the more dense the material the faster the sound is.
Physics
1 answer:
elena55 [62]3 years ago
8 0
The answer is the second option or B.
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He angular position of a swinging door is described by θ = 5.00 + 10.0 t + 2.00 t2 [rad]. (a) determine the angular position, an
Inessa05 [86]
(a) The angular position of the door is described by
\theta(t)=5+10t+2t^2 [rad]

The angular velocity is given by the derivative of the angular position:
\omega(t)=10+4t [rad/s]

While the angular acceleration is given by the derivative of the angular velocity:
\alpha(t)=4 [rad/s^2]

We want to find the values of these quantities at time t=3.00 s, so we must substitute t=3.00 s into the expressions for \theta, \omega, \alpha:
\theta(3.00 s)=5+(10)(3.00 s)+2(3.00s)^2 = 53 rad
\omega(3.00 s)=10+4(3.00s)=22 rad/s
\alpha(3.00s)=4 rad/s^2

(b) The door starts from rest, so its initial angular velocity is \omega_i=0 rad/s, and it reaches a final angular velocity of \omega_f=0.750 rad/s with an angular acceleration of \alpha=0.560 rad/s^2. We can find the angular distance covered by the door by using the following relationship:
2 \alpha \theta = \omega_f^2 - \omega_i^2
from which we find
\theta= \frac{\omega_f^2}{2 \alpha}= \frac{(0.750 rad/s)^2}{2 \cdot 0.560 rad/s^2} =0.502 rad
6 0
3 years ago
The mass of a robot is 34 kg. It is traveling at 2 m/s when it collides with the fence. According to Newton's third law, which d
kherson [118]
Here, Force = m * a = 34 * 2 = 68 N

According to Newton's third law, fence will exert equal and opposite force (by direction) on the robot.

In short, Your Answer would be Option C) <span>The robot exerts a force of 68 N on the fence; the fence exerts a force of 68 N on the robot. 

Hope this helps!</span>
6 0
3 years ago
How much heat is absorbed by a 72g iron skillet when its temperature rises from 14oc to 24oc?
murzikaleks [220]
<h2>Answer</h2>

The answer to this question is <u>331.59 J</u>

<h2>Explanation</h2>

As we know Specifi Heat formula that

Q=mCpΔT

The mass is = 72 g (72/1000 = 0.072 kg)

ΔT = 24-14 = 10^{o}C

Cp for iron = 460.548 J/(kg^{o}C)

Put the values in formula

Q = 0.072 * 10 * 460.548

Q = 331.59 J

So, absorbed heat will be 331.59 J


6 0
3 years ago
The coil has a radius of 8 cm and 110 turns. While moving the magnet closer towards the coil, at a certain point in time, the vo
lianna [129]

Answer:

The magnitude of the rate of change of the flux through the coil is 2.82 x 10⁻³ T.m²/s

Explanation:

Given;

radius of coil, r = 8 cm = 0.08 m

number of turns of the coil, N = 110 turns

the induced emf through the coil, E = -310mV

The induced emf through the coil is given by;

E = - N\frac{d \phi}{dt} \\\\\frac{d \phi}{dt} = \frac{E}{-N}

Where;

dФ/dt is the magnitude of the rate of change of the flux through the coil

\frac{d\phi}{dt} = \frac{-0.31}{110} \\\\\frac{d\phi}{dt} =2.82*10^{-3} \ T.m^2/s

Therefore, the magnitude of the rate of change of the flux through the coil is 2.82 x 10⁻³ T.m²/s

8 0
3 years ago
Two monatomic gases, helium and neon, are mixed in a sealed container and brought into thermal equilibrium at temperature T . If
klasskru [66]

Answer:

A. all the atoms have the same average speed

Explanation:

The entropy of the two monatomic gases (helium and neon) depends on temperature of the  sealed container. Increase in temperature of the container increases the speed of the atoms while decrease in temperature of the container decreases the speed of the atoms. Also at constant temperature, all the gaseous atoms will move at a constant speed (that is randomly or no direction).

Since, the sealed container was brought into thermal equilibrium, meaning that the temperature of the system is constant. Thus, all the atoms have the same average speed.

3 0
3 years ago
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