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3 years ago

What electromagnetic waves are used in these applications?

1 answer:

6 0

Diagnosing illnesses: Radio Waves
Warming and cooking food: microwaves
Transmitting data from remote controls to televisions: infrared waves

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According to Bode’s Law a planet is missing between Jupiter and Saturn. True False

defon

Bode law, a planet was believed to exist between .... An Astronomer's Account of the Missing Planet Between Mars and Jupiter as Interpreted Jupiter ·Saturn · Uranus · Neptune.

6 0

3 years ago

A charge of Q is fixed in space. A second charge of q was first placed at a distance r1 away from Q. Then it was moved along a s

topjm [15]

Answer:

$\Delta U = \frac{Qq}{4\pi\epsilon_0}(\frac{1}{r_2^2}-\frac{1}{r_1^2})$

Explanation:

The electrostatic potential energy is given by the following formula

$U = \frac{1}{4\pi\epsilon_0}\frac{q_1q_2}{r^2}$

Now, we will apply this formula to both cases:

$U_1 = \frac{1}{4\pi\epsilon_0}\frac{Qq}{r_1^2}\\U_2 = \frac{1}{4\pi\epsilon_0}\frac{Qq}{r_2^2}$

So, the change in the potential energy is

$\Delta U = U_2 - U_1 = \frac{Qq}{4\pi\epsilon_0}(\frac{1}{r_2^2}-\frac{1}{r_1^2})$

7 0

3 years ago

A mass of 5kg starts from rest and pulls down vertically on a string wound around a disk-shaped, massive pulley. The mass of the

Paha777 [63]

Answer:

c. V = 2 m/s

Explanation:

Using the conservation of energy:

$E_i =E_f$

so:

Mgh = $\frac{1}{2}IW^2 +\frac{1}{2}MV^2$

where M is the mass, g the gravity, h the altitude, I the moment of inertia of the pulley, W the angular velocity of the pulley and V the velocity of the mass.

Also we know that:

V = WR

Where R is the radius of the disk, so:

W = V/R

Also, the moment of inertia of the disk is equal to:

I = $\frac{1}{2}MR^2$

I = $\frac{1}{2}(5kg)(2m)^2$

I = 10 kg*m^2

so, we can write the initial equation as:

Mgh = $\frac{1}{2}IV^2/R^2 +\frac{1}{2}MV^2$

Replacing the data:

(5kg)(9.8)(0.3m) = $\frac{1}{2}(10)V^2/(2)^2 +\frac{1}{2}(5kg)V^2$

solving for V:

(5kg)(9.8)(0.3m) = $V^2(\frac{1}{2}(10)1/4 +\frac{1}{2}(5kg))$

V = 2 m/s

8 0

3 years ago

Dry cells become soft even when not in use. Explain.

mamaluj [8]

This is possible due to self-discharge. Very small internal currents inevitably occur in these cells over time and they will eventually exhaust the chemistry.

4 0

3 years ago

How many times louder is the intensity of sound at a rock concert in comparison with that of a whisper, if the two intensity lev

Phoenix [80]

Answer:

5 × 10¹⁰ or 5 billion times louder is the intensity of sound at a rock concert in comparison with that of a whisper

Explanation:

Given that at a rock concert;

the intensity of sound is 110 dB compared to a whisper of 3 dB

Now; how many times louder will that of the whisper be compared to the sound of the rock concert

Using the formula for calculating decibels (dB);

For 110 dB

dB = 10log₁₀(W)

110 dB = $10^{(110/10)}$

110 dB = 10¹¹

For 3dB

dB = 10log₁₀(W)

3 dB = $10^{(3/10)}$

3 dB = 2

Now:

(110/3)dB = 10¹¹/2

(110/3)dB = 5 × 10¹⁰ or 5 billion times louder is the intensity of sound at a rock concert in comparison with that of a whisper

7 0

3 years ago