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3 years ago

What is the wavelenght and the frequencen of walkie-talkie?

1 answer:

8 0

Nowadays, most of the walkie talkies ... and all R/C models ... operate in the "Family Radio Service" (FRS) band. That's 46-49 MHz. The wavelength is 6.12-6.52 meters.

You might be interested in

At what temperature the semiconductor behaves like conductor?

hammer [34]

Answer:

A semiconductor acts like an ideal insulator at absolute zero temperature that is at zero kelvin. It is because the free electrons in the valence band of semiconductors will not carry enough thermal energy to overcome the forbidden energy gap at absolute zero.

5 0

3 years ago

Compare an earthquake with a Richter scale magnitude of 5.5 to one with a magnitude of 7.5.

maksim [4K]

The 7.5 is a 100 times stronger than the 5.5 . The 100 comes from the increase in scale from 5.5 to 7.5 which is an increase of two so you multiply the strength of the weaker earthquake 10^7-5=10^2=100 and that gives you the strength of the stronger earthquake!

7 0

3 years ago

At the beginning of a unit on forces, Ms. Alton is leading a class discussion asking her students

VMariaS [17]

Answer:

(iv), (v), (vi) would be incorrect.

Explanation:

(iv) Force isn't transferred from one colliding object to another, but momentum can be.

(v) An object doesn't stop immediately a force stops acting on it. Think of a thrown ball.

(vi) For an object not to move, it means that the net force on the object is zero, and not necessarily that there are no forces acting on the object. For example, an object could be pushed on one side, and be pushed on the other side with an equal force in the opposite direction. The forces would cancel each other and the net force would be zero.

The rest should be correct.

6 0

3 years ago

A ball is tossed with enough speed straight up so that it is in the air several seconds. (a) What is the velocity of the ball wh

irina1246 [14]

(a) Zero

When the ball reaches its highest point, the direction of motion of the ball reverses (from upward to downward). This means that the velocity is changing sign: this also means that at that moment, the velocity must be zero.

This can be also understood in terms of conservation of energy: when the ball is tossed up, initially it has kinetic energy

$K=\frac{1}{2}mv^2$

where m is the ball's mass and v is the initial speed. As it goes up, this kinetic energy is converted into potential energy, and when the ball reaches the highest point, all the kinetic energy has been converted into potential energy:

$U=mgh$

where g is the gravitational acceleration and h is the height of the ball at highest point. At that point, therefore, the potential energy is maximum, while the kinetic energy is zero, and so the velocity is also zero.

(b) 9.8 m/s upward

We can find the velocity of the ball 1 s before reaching its highest point by using the equation:

$a=\frac{v-u}{t}$

where

a = g = -9.8 m/s^2 is the acceleration due to gravity, which is negative since it points downward

v = 0 is the final velocity (at the highest point)

u is the initial velocity

t = 1 s is the time interval

Solving for u, we find

$u=v-at = 0 -(-9.8 m/s^2)(1 s)= +9.8 m/s$

and the positive sign means it points upward.

(c) -9.8 m/s

The change in velocity during the 1-s interval is given by

$\Delta v = v -u$

where

v = 0 is the final velocity (at the highest point)

u = 9.8 m/s is the initial velocity

Substituting, we find

$\Delta v = 0 - (+9.8 m/s)=-9.8 m/s$

(d) 9.8 m/s downward

We can find the velocity of the ball 1 s after reaching its highest point by using again the equation:

$a=\frac{v-u}{t}$

where this time we have

a = g = -9.8 m/s^2 is the acceleration due to gravity, still negative

v is the final velocity (1 s after reaching the highest point)

u = 0 is the initial velocity (at the highest point)

t = 1 s is the time interval

Solving for v, we find

$v = u+at = 0 +(-9.8 m/s^2)(1 s)= -9.8 m/s$

and the negative sign means it points downward.

(e) -9.8 m/s

The change in velocity during the 1-s interval is given by

$\Delta v = v -u$

where here we have

v = -9.8 m/s is the final velocity (1 s after reaching the highest point)

u = 0 is the initial velocity (at the highest point)

Substituting, we find

$\Delta v = -9.8 m/s - 0=-9.8 m/s$

(f) -19.6 m/s

The change in velocity during the overall 2-s interval is given by

$\Delta v = v -u$

where in this case we have:

v = -9.8 m/s is the final velocity (1 s after reaching the highest point)

u = +9.8 m/s is the initial velocity (1 s before reaching the highest point)

Substituting, we find

$\Delta v = -9.8 m/s - (+9.8 m/s)=-19.6 m/s$

(g) -9.8 m/s^2

There is always one force acting on the ball during the motion: the force of gravity, which is given by

$F=mg$

where

m is the mass of the ball

g = -9.8 m/s^2 is the acceleration due to gravity

According to Newton's second law, the resultant of the forces acting on the body is equal to the product of mass and acceleration (a), so

$mg = ma$

which means that the acceleration is

$a= g = -9.8 m/s^2$

and the negative sign means it points downward.

7 0

3 years ago

PLEASE HELP QUICKLY 50 POINTS<br> Fracturing can emit ______waves through the ground.

drek231 [11]

Answer:

Fracturing can emit seismic waves through the ground.

Explanation:

I believe the answer is seismic, I've studied this before.

5 0

3 years ago