Answer:
- Direct current is a current in which electrons flow in one direction only
- Alternating current is a current in which the direction of the electron flow reverses periodically - so, half a cycle forward, half a cycle backward
There are several advantages of using alternating currents for the transmission of electricity across a country, over large distances. The main advantages are:
- The voltage of alternating currents can be easily increased/decreased by using transformers. For instance, a transformer is used at the beginning of the transmission line to increase the voltage (electricity is transmitted at high voltage in order to reduce dissipated power), and then another transformer is used before the electricity enters the houses, in order to decrease the voltage. Transformers only work with alternating currents.
- It is easy to interrupt the flow of an alternating current, because its value naturally becomes zero every half a cycle, so this is useful in case the current must be interrupted.
Answer:
<em>500Joules</em>
Explanation:
Kinetic energy = 1/2mv²
m is the mass of the wood
v is the velocity
Given
Mass = 10kg
Velocity v = 10m/s
Substitute into the formula and get KE
KE = 1/2 * 10 * 10²
KE = 1/2 * 1000
KE = 500Joules
<em>Hence the kinetic energy of the wood during delivery is 500Joules</em>
<span>It is LandSat, a NASA based satelite that records, on a daily basis, multiple reflected wavelengths from the Earth's surface. The satelite measures reflection from both land and ocean upon the Earth. The system is utilised by scientists an policy makers around the world. </span>
Answer:
El mango llega al suelo a una velocidad de 329.982 metros por segundo.
Explanation:
El mango experimenta un movimiento de caída libre, es decir, un movimiento uniformemente acelerado debido a la gravedad terrestre, despreciando los efectos de la viscosidad del aire y la rotación planetaria. Entonces, la velocidad final del mango, es decir, la velocidad con la que llega al suelo, se puede determinar mediante la siguiente fórmula cinemática:
(1)
Donde:
- Velocidad inicial, en metros por segundo.
- Velocidad final, en metros por segundo.
- Aceleración gravitacional, en metros por segundo al cuadrado.
- Tiempo, en segundos.
Si sabemos que 
, 
y 
, entonces la velocidad final del mango es:
El mango llega al suelo a una velocidad de 329.982 metros por segundo.
