Responder:
35,2 ohm.
Explicación:
Dado:
La resistencia específica del conductor es,
La longitud del conductor es,
El área de la sección transversal del conductor es,
Sabemos que la resistencia de un conductor es directamente proporcional a su longitud e inversamente proporcional al área de la sección transversal.
Por lo tanto, la resistencia se puede expresar como:
![R=\frac{\rho\times l}{A}](https://tex.z-dn.net/?f=R%3D%5Cfrac%7B%5Crho%5Ctimes%20l%7D%7BA%7D)
Ahora, conecte los valores dados y resuelva para 'R'. Esto da,
![R=\frac{1.6\times 10^{-6}\ ohm\cdot m\times 110\ m}{5\times 10^{-6}\ m^2}\\\\R=35.2\ ohm](https://tex.z-dn.net/?f=R%3D%5Cfrac%7B1.6%5Ctimes%2010%5E%7B-6%7D%5C%20ohm%5Ccdot%20m%5Ctimes%20110%5C%20m%7D%7B5%5Ctimes%2010%5E%7B-6%7D%5C%20m%5E2%7D%5C%5C%5C%5CR%3D35.2%5C%20ohm)
Por lo tanto, la resistencia del conductor es de 35,2 ohm.
Answer:
96%
Explanation:
To find the values of the motor efficiency you use the following formula:
![E=\frac{P_o}{P_i}100](https://tex.z-dn.net/?f=E%3D%5Cfrac%7BP_o%7D%7BP_i%7D100)
P_o: output power = 864J/0.5min=864J/30s=28.8W
P_i: input power = I*V = (3A)(12V) = 36W
By replacing this values you obtain:
![E=\frac{28.8W}{30W}*100=96\%](https://tex.z-dn.net/?f=E%3D%5Cfrac%7B28.8W%7D%7B30W%7D%2A100%3D96%5C%25)
hence, the motor efficiency is about 96%
traslation:
Pentru a găsi valorile eficienței motorului, utilizați următoarea formulă:
P_o: putere de ieșire = 864J / 0.5min = 864J / 30s = 28.8W
P_i: putere de intrare = I * V = (3A) (12V) = 36W
Înlocuind aceste valori obțineți:
prin urmare, eficiența motorului este de aproximativ 96%
In a stationary situation, the weight of person is
![W=mg=(62 kg)(9.81 m/s^2) = 608.2 N](https://tex.z-dn.net/?f=W%3Dmg%3D%2862%20kg%29%289.81%20m%2Fs%5E2%29%20%3D%20608.2%20N)
This is the weight "felt" by the scale, which is basically the normal reaction applied by the scale on the person, and which uses the value of g (9.81) as reference to convert the weight (602.8 N) into a mass (62 kg).
When the person is in the elevator, the scale says 77 kg. The scale is still using the same value of conversion (9.81), so the apparent weight "felt" by the scale is
![W' = m'g=(77 kg)(9.81 m/s^2)=755.4 N](https://tex.z-dn.net/?f=W%27%20%3D%20m%27g%3D%2877%20kg%29%289.81%20m%2Fs%5E2%29%3D755.4%20N)
This is the normal reaction applied by the scale on the person, and which is directed upward. Besides this force, there is still the weight W of the person, acting downward. So, if we use Newton's second law:
![\sum F = ma](https://tex.z-dn.net/?f=%5Csum%20F%20%3D%20ma)
![W-W'=ma](https://tex.z-dn.net/?f=W-W%27%3Dma)
where a is the acceleration of the elevator. If we solve for a, we find
![a= \frac{W-W'}{m}= \frac{608.2N-755.4N}{62 kg}=-2.37 m/s^2](https://tex.z-dn.net/?f=a%3D%20%5Cfrac%7BW-W%27%7D%7Bm%7D%3D%20%5Cfrac%7B608.2N-755.4N%7D%7B62%20kg%7D%3D-2.37%20m%2Fs%5E2%20%20)
The negative sign means the acceleration is in the opposite direction of g (which we take positive), so it means the elevator is going upward.
A material that has high resistance to the flow of electric current is called an electric resistor