Ask question

Ask question

All categories

2 years ago

15

Una barra de hierro cuya longitud inicial es de 2m se le incrementa su temperatura de 20 °C a 120 °C ¿Cuál es la longitud final

de la barra? (considera que el coeficiente de dilatación del hierro) es 1,2 x 10-5 1/°C ( 3 puntos)

1 answer:

Ksivusya [100]2 years ago

8 0

Answer:

1.9976 m

Explanation:

An iron bar whose initial length is 2m has its temperature increased from 20 ° C to 120 ° C. What is the final length of the bar? (consider that the coefficient of expansion of iron) is 1.2 x 10-5 1 / ° C (3 points)

Given that,

Initial length of an iron bar, $L_0=2\ m$

The temperature increased from 20°C to 120°C

The coefficient of expansion of iron is $1.2\times 10^{-5}\ /^{\circ} C$

We need to find the final length of the bar.

The linear expansion equation is given by :

$\Delta L=\alpha L\Delta T$

Where $\Delta L$ is the change in length

$\Delta L=1.2\times 10^{-5}\times 2\times (120-20)\\\\=0.0024\ m$

Also, $\Delta L = L_o-L$

L is final length

$0.0024= 2-L\\\\L=2-0.0024\\\\=1.9976\ m$

So, the final length of the bar is 1.9976 m

You might be interested in

How can you use a magnet to induce a current?

Furkat [3]

A coil of wire with a current flowing thru it becomes a magnet

3 0

3 years ago

Read 2 more answers

NASA launches a probe with a mass of 15,000 kg to another planet more massive than Earth. Which statement is true about the prob

vivado [14]

Answer: The weight of the probe will increase.

8 0

2 years ago

6) Find the speed a spherical raindrop would attain by falling from 4.00 km. Do this:a) In the absence of air dragb) In the pres

sleet_krkn [62]

We are asked to determine the velocity of a rain drop if it falls from 4 km.

To do that we will use the following formula:

$2ah=v_f^2-v_0^2$

Where:

$\begin{gathered} a=\text{ acceleration} \\ h=\text{ height} \\ v_f,v_0=\text{ final and initial velocity} \end{gathered}$

If we assume the initial velocity to be 0 we get:

$2ah=v_f^2$

The acceleration is the acceleration due to gravity:

$2gh=v_f^2$

Now, we take the square root to both sides:

$\sqrt{2gh}=v_f$

Now, we substitute the values:

$\sqrt{2(9.8\frac{m}{s^2})(4000m)}=v_f$

solving the operations:

$280\frac{m}{s}=v$

Therefore, the velocity without air drag is 280 m/s.

Part B. we are asked to determine the velocity if there is air drag. To do that we will use the following formula:

$F_d=\frac{1}{2}C\rho_{air}Av^2$

Where:

$\begin{gathered} F_d=drag\text{ force} \\ C=\text{ constant} \\ \rho_{air}=\text{ density of air} \\ A=\text{ area} \\ v=\text{ velocity} \end{gathered}$

We need to determine the drag force. To do that we will use the following free-body diagram:

Since the velocity that the raindrop reaches is the terminal velocity and its a constant velocity this means that the acceleration is zero and therefore the forces are balanced:

$F_d=mg$

Now, we determine the mass of the raindrop using the following formula:

$m=\rho_{water}V$

Where:

$\begin{gathered} \rho_{water}=\text{ density of water} \\ V=\text{ volume} \end{gathered}$

The volume is the volume of a sphere, therefore:

$m=\rho_{water}(\frac{4}{3}\pi r^3)$

Since the diameter of the raindrop is 3 millimeters, the radius is 1.5 mm or 0.0015 meters. Substituting we get:

$m=(0.98\times10^3\frac{kg}{m^3})(\frac{4}{3}\pi(0.0015m)^3)$

Solving the operations:

$m=1.39\times10^{-5}kg$

Now, we substitute the values in the formula for the drag force:

$F_d=(1.39\times10^{-5}kg)(9.8\frac{m}{s^2})$

Solving the operations:

$F_d=1.36\times10^{-4}N$

Now, we substitute in the formula:

$1.36\times10^{-4}N=\frac{1}{2}C\rho_{air}Av^2$

Now, we solve for the velocity:

$\frac{1.36\times10^{-4}N}{\frac{1}{2}C\rho_{air}A}=v^2$

Now, we substitute the values. We will use the area of a circle:

$\frac{1.36\times10^{-4}N}{\frac{1}{2}(0.45)(1.21\frac{kg}{m^3})(\pi r^2)}=v^2$

Substituting the radius:

$\frac{1.36\cdot10^{-4}N}{\frac{1}{2}(0.45)(1.21\frac{kg}{m^{3}})(\pi(0.0015m)^2)}=v^2$

Solving the operations:

$70.67\frac{m^2}{s^2}=v^2$

Now, we take the square root to both sides:

$\begin{gathered} \sqrt{70.67\frac{m^2}{s^2}}=v \\ \\ 8.4\frac{m}{s}=v \\ \end{gathered}$

Therefore, the velocity is 8.4 m/s

7 0

1 year ago

2. a) Force affects the body and results in different changes. The grid given below

postnew [5]

Answer:

Please find the answer in the explanation

Explanation:

Given that Force affects the body and results in different changes.

The grid that has the words related to the effects of force are :

a) Force could be a push or a pull.

c) Force has magnitude as well as direction.

e) Force acting on an object may cause a change in its state of motion or a change in its shape.

f) A force can act on an object with or without being in contact with it.

8 0

3 years ago

Obligation of reasearchers to review true or fasle

MrMuchimi

I think if I was a researcher I would review my work or the sources I use, True

5 0

3 years ago