All categories

2 years ago

Which of the following electromagnetic waves is not used for communication?

1 answer:

8 0

Microwaves and radio waves are employed in radio and satellite communications while infrared waves are used in remote controls and infrared features of new phones and other electrons. However, gamma rays have far too much energy and cause damage to the body. They are not used in communication.
The answer is A.

You might be interested in

In the figure, a weightlifter's barbell consists of two identical small but dense spherical weights, each of mass 50 kg. These w

kondaur [170]

The moment of inertia is $24.8 kg m^2$

Explanation:

The total moment of inertia of the system is the sum of the moment of inertia of the rod + the moment of inertia of the two balls.

The moment of inertia of the rod about its centre is given by

$I_r = \frac{1}{12}ML^2$

where

M = 24 kg is the mass of the rod

L = 0.96 m is the length of the rod

Substituting,

$I_r = \frac{1}{12}(24)(0.96)^2=1.84 kg m^2$

The moment of inertia of one ball is given by

$I_b = mr^2$

where

m = 50 kg is the mass of the ball

$r=\frac{L}{2}=\frac{0.96}{2}=0.48 m$ is the distance of each ball from the axis of rotation

So we have

$I_b = (50)(0.48)^2=11.5 kg m^2$

Therefore, the total moment of inertia of the system is

$I=I_r + 2I_b = 1.84+ 2(11.5)=24.8 kg m^2$

Learn more about inertia:

brainly.com/question/2286502

brainly.com/question/691705

#LearnwithBrainly

6 0

2 years ago

Which property of gases allows them to be stored at high concentrations in a bottle of air freshener?

Agata [3.3K]

Answer:

Explanation:

the ability for gases to compress is extremely helpful it allows tanks of oxygen to hold enough air for up to two hours and the strange thing about compression is that it allows some liquids to stay liquid at their boiling point allowing liquid nitrogen to stay liquid at room temperature

5 0

2 years ago

a 230 kg roller coaster reaches the top of the steepest hill with a speed of 6.2 km/h. It then descends the hill, which is at an

igor_vitrenko [27]

Answer: 81.619 kJ

Explanation:

Given

Mass of roller coaster is $m=230\ kg$

It reaches the steepest hill with speed of $u=6.2\ km/h\ or \ 1.72\ m/s$

Hill to bottom is 51 m long with inclination of $45^{\circ}$

Height of the hill is $h=51\sin 45^{\circ}=36.06\ m$

Conserving energy to get kinetic energy at bottom

Energy at top=Energy at bottom

$\Rightarrow K_t+U_t=K_b+U_b\\\Rightarrow \dfrac{1}{2}mu^2+mgh=K_b+0\\\\\Rightarrow K_b=0.5\times 230\times 1.72^2+230\times 9.8\times 36.06\\\Rightarrow K_b=340.216+81,279.24\\\Rightarrow K_b=81,619.456\ J\\\Rightarrow K_b=81.619\ kJ$

8 0

2 years ago

If 478 watts of power are used in 14 seconds,how much work was done

zepelin [54]

Answer:

6692J

Explanation:

Power is defined as the rate at which work is being done.

So,

Power = $\frac{workdone}{time }$

Work done = Power x time

Given parameters:

Power = 478watts

Time = 14s

So;

Work done = 478 x 14 = 6692J

6 0

2 years ago

(c)

grigory [225]

Answer:

Both AC and DC describe types of current flow in a circuit. In direct current (DC), the electric charge (current) only flows in one direction. Electric charge in alternating current (AC), on the other hand, changes direction periodically.

7 0

1 year ago