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Semenov [28]
3 years ago
5

A railroad car of mass 2.50 3 104 kg is moving with a speed of 4.00 m/s. It collides and couples with three other coupled railro

ad cars, each of the same mass as the single car and moving in the same direction with an initial speed of 2.00 m/s. (a) What is the speed of the four cars after the collision? (b) How much mechanical energy is lost in the collision?
Physics
1 answer:
ipn [44]3 years ago
4 0

Answer:2.5 m/s

37.5KJ

Explanation:

Let u_1, u_2 , v_f be the initial velocity of rail road car ,coupled cars & Final velocity of system respectively.

m=2.50\times 10^{4}

Conserving momentum

mu_1+3mu_2=4mv_f

4m+6m=4mv_f

v_f=2.5 m/s

Therefore Final velocity of system is 2.5m/s

(b)Mechanical Energy lost =Initial Kinetic Energy -Final Kinetic Energy

Initial Kinetic Energy=\frac{1}{2}m\left ( 4^2\right )+\frac{1}{2}m\left ( 2^2\right )=14m J

Final Kinetic Energy=\frac{1}{2}4m\left ( 2.5^2\right )=12.5m J

Mechanical Energy lost=14m-12.5m=3.75\times 10^4=37.5 KJ

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Un alumno menciona que al abrir la ventana de su casa sintió cómo el frío ingresaba a su cuerpo. Menciona cuál es la verdadera r
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Answer:

My believe the answer is

A.) or B.)

Explanation:

Here is why I think A is the answer.

If we use the process of elimination, it would look like this,

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<em>This answer has nothing to do with the question, plus it is very false, our body heat is not enough to overcome the very cold temperature from outside.</em>

d) Porque la temperatura del aire es igual a la temperatura del cuerpo.

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Answer:

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A Carnot engine operates with an efficiency of 26.0% when the temperature of its cold reservoir is 281 K. Assuming that the temp
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Answer:

The temperature of cold reservoir should be 246.818 K for efficiency of 35%

Explanation:

In first case we have given efficiency of Carnot engine = 26 % = 0.26

Temperature of cold reservoir T_L=281K

We know that efficiency of Carnot engine is given by

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And temperature of hot reservoir is same so T_H=379.72K

So 0.35=1-\frac{T_L}{379.72}

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So the temperature of cold reservoir should be 246.818 K for efficiency of 35%

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