<h2>Answer:</h2>
The part of the electromagnetic spectrum usually used for communication is of radio waves, infrared waves and microwaves.
But most common waves used in communication are radio waves.
<h3>Explanation:</h3>
- Radio waves are used to transmit television and radio programmes.
- While microwaves are used for mobile phones and Wi-Fi.
- Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light.
- Radio waves have frequencies as high as 300 gigahertz (GHz) to as low as 30 hertz (Hz).
Answer:
When charged particles from the sun strike atoms in Earth's atmosphere, they cause electrons in the atoms to move to a higher-energy state. When the electrons drop back to a lower energy state, they release a photon: light. This process creates the beautiful aurora, or northern lights.
Explanation:
<span>FIRST SECTION
You should use the formula for uniformly accelerated linear movement.
Initial speed is 0 because it starts from rest.
d=(1/2)*a*t^2+vo*t =(1/2)*(4.0 m/s^2)*(3s)^2+0*3s=(1/2)*(4.0 m/s^2)*3^2*s^2+0=2.0 m*9=18m
You can calculate the final speed with the other formula:
v=a*t+vo=(4.0 m/s^2)*(3s)+0=(4.0 m/s)*(3)=12m/s
SECOND SECTION
You should use the formula for uniform linear movement.
Velocity is a constant: it remains in 12m/s.
d=v*t=12m/s*2s=12m*2=24m
THIRD SECTION
We should use the same formulas as the first section, but with different numbers.
Initial velocity will be 12m/s, and then velocity will start to decrease until it gets to 0.
We don’t know what the time is for this section.
Acceleration is negative, because it’s slowing down.
v=a*t+vo
0=-3.0 m/s^2*t+12m/s
3.0 m/s^2*t=12m/s
t=(12m/s)/(3.0 m/s^2)=4(1/s)/(1/s^2)=4s^2/s=4s
Now let’s use that time in the other formula:
d=(1/2)*a*t^2+vo*t =(1/2)*(-3.0 m/s^2)*(4s)^2+(12m/s)*3s=(-1.5 m/s^2)*4^2*s^2+12*3m*s/s=-1.5 m*4^2+36m=-1.5*16m+36m=-24m+36m=12m
Now let’s add the 3 stages:
d=18m+24m+12m=54m
</span>
use the formula F = ma
F:force m:mass a:acceleration
so
f= 27.6 kg *3.3 m/s^2
= 91.08 N