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Fofino [41]
3 years ago
6

An open train car moves with speed 18.5 m/s on a flat frictionless railroad track, with no engine pulling the car. It begins to

rain. The rain falls straight down and begins to fill the train car.Does the speed of the car decrease , increase ,or stay the same ? Explain.
Physics
1 answer:
olga2289 [7]3 years ago
3 0

Answer:

The speed decreases.

Explanation:

This can be explained using the conservation of linear momentum.

Since there is no friction, the initial moment of the train must be equal to its linear moment after it is filled with water.

the initial linear momentum is

m_{1}v_{1}

where m_{1} is the initial mass of the train, and v_{1} the initial speed of the train.

And linear momentum after the water filled the train car is

m_{2}v_{2}

where m_{2} is mass of the train after the  rain, and v_{2} the speed of the train after the rain

<u>the equality must be fulfilled:</u>

m_{1}v_{1}=m_{2}v_{2}

We know that if water is added to the train, m_{2} that is the mass after the water is added, is greater than m_{1} which is the mass of the train without the water.

Therefore, in order for the conservation of the linear momentum to be fulfilled: m_{1}v_{1}=m_{2}v_{2}

the speed after the water is added (v_{2} ) must be smaller than the initial train speed (v_{1} ) . So the speed of the car decreases.

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Answer:

The value is }  N  =  66 \  blocks

Explanation:

From the question we are told that

The weight of the block is W_b  = 100 \  N

The dimension of the block is d =  0.400 m  \ X  \ 0.250 \  m  \  X  \ 0.130 \ m

Generally two atmosphere is equivalent to

P_{2atm} =  2 *  1.013 *10^{5} =  202600 \  N/m^2

Generally 1 atm = 1.013 *10^{5} N/m^2

The area of the block would be evaluated using width and height because we need for the smaller surface to be in contact with the ground in order to maximize the pressure and minimize number of blocks

So

A =  0.250 *  0.130

=> A =  0.0325 \  m^2

Generally the force due to this blocks is mathematically represented as

F =  N  *  W_b

Here N is the number of blocks

So

}  202600 =  \frac{N  *  100 }{ 0.0325}

=>   }  N  =  66 \  blocks

3 0
3 years ago
A roller coaster's velocity at the top of the hill is 10 m/s. Two seconds later it reaches the bottom of the hill with a velocit
svet-max [94.6K]

your answer is 8 m / sec²

5 0
2 years ago
The height of the Washington Monument is measured to be 170 m on a day when its temperature is 35.0°C. What will the change in i
Alecsey [184]

Answer:

The deformation is 0.088289 m

The final height of the monument is 170-0.088289 = 169.911702 m

Explanation:

Thermal coefficient of marble varies between (5.5 - 14.1) ×10⁻⁶/K = α

So, let us take the average value

(5.5+14.1)/2 = 9.8×10⁻⁶ /K

Change in temperature = 35-(-18) = 53 K = ΔT

Original length = 170 m = L

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The deformation is 0.088289 m

The final height of the monument is 170-0.088289 = 169.911702 m (subtraction because of cooling)

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3 years ago
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Answer is B. According to the equation of motion s = vt + 1/2 at2 Where s is distance covered, v is velocity, a is acceleration and t is time taken. So, by putting all the values, we get s = (20)(5) + 1/2 (3)(5)2 s = 100 + 1/2 (3)(25) s = 100 + 1/2 75 s = 100 + 37.5 s = 137.5 meters



7 0
3 years ago
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Answer:

I'm Pretty sure the answer your looking for is C

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