PHYSICS HIGH SCHOOL

Sa se calculeze caldura degajata de un fier de calcat dace este alimentat la 220v si este parcurs de un curent electric de 100 a. Se stie ca acesta functioneaza 25 de min

Answers

Answer 1

Answer:

Answer

33,000,000 joules or 33MJ

Explanation:

The formula for calculating the heat released by a substance is expressed as shown below;

where;

Q is the amount of heat released

p is the power expended

t is the time it takes

$Since P = current * voltage\nP = IV$

Then;

$Q = IVt$

Given the current I = 100A, supply voltage V = 220V and required time t = 25mins

t = 25 * 60 = 1500 seconds

Substituting these values in the formula that we have;

$Q = 100 * 220 * 1500\nQ = 22000*1500\nQ = 33,000,000Joules\ or\ 33MJ$

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The frequency of wave A is 250 hertz and the wavelength is 30 centimeters. The frequency of wave B is260 hertz and the wavelength is 25 centimeters. Which is the faster wave?

Answers

Wave A will be faster than the wave B because $V_A > V_B$

What is the frequency of the wave?

The frequency of the wave is defined as the cycle completed by the wave per second.

Now it is given in the question:

Frequency of wave A = 250 hertz

The wavelength of wave A= 30 cm

Frequency of wave B = 260 hertz

The wavelength of wave B= 25 cm

Now for finding which wave is faster we will calculate the velocity of the wave.

For Wave A

$V_A=f*\lambda=250* 30=7500\ (cm)/(s)$

For wave B

$V_B=f*\lambda=260* 25=6500\ (cm)/(s)$

We can see that the velocity of wave A is higher than the velocity of wave B.

Thus wave A will be faster than the wave B because $V_A > V_B$

To know more about the frequency of waves follow

brainly.com/question/12215474

Use the equation v=fλ
Wave A
250×30×10^-2=75 m/s
Wave B
260×25×10^-2=65 m/s

Therefore
Wave A is faster

A dock worker loading crates on a ship finds that a 24 kg crate, initially at rest on a horizontal surface, requires a 65 N horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 50 N is required to keep it moving with a constant speed. The acceleration of gravity is 9.8 m/s 2 . Find the coefficient of static friction between crate and floor.

Answers

Answer:

0.276

Explanation: Here we have to consider the kinetic friction force acting on the body. If it is going at a constant speed according to newton's 1 st law. There was'not net force induced at the system. There for kinetic friction foce must be equal to the 50N .

But here we have been asked to get cofficient of static friction . There for you have to get static friction force. It should be 65N.

Mass of the object is 24. Then the reaction between surface and the object would be 24*9.8 = 235.2 N

There for using this,

Static friction force = Cofficient of static friction * Reaction

Cofficient of static friction = 65/235.2

= 0.276

Answer:

$\mu_s=0.276$

$\mu_k=0.213$

Explanation:

It is given that,

Mass of the crate, m = 24 kg

Force acting on the crate when it is at rest, $F_r=65\ N$

When the crate is in motion, force acting on the crate, $F_m=55\ N$

To find,

The coefficient of static friction between crate and floor

Solution,

When the crate is at rest, the force acting on the crate is given by :

$F_r=\mu_sN$

$65=\mu_s* 24* 9.8$

$\mu_s=0.276$

When the crate is in motion, the force acting on the crate is given by :

$F_s=\mu_kN$

$50=\mu_k* 24* 9.8$

$\mu_k=0.213$

Hence, this is the required solution.

The atomic number of beryllium (Be) is 4, and the atomic number of barium (Ba) is 56. Which comparison is best supported by this information?

Answers

Answer;

The comparison that would be best is;

They are in the same group because they have similar chemical properties, but they are in different periods because they have very different atomic numbers.

Explanation;

Beryllium (Be) is an element is the periodic table with an atomic number of 4, which means it has 4 protons in the nucleus and also 4 electrons in the energy levels, since the number of protons is equal to the number of electrons.
Beryllium has an electron configuration of 2: 2, which means it has two valence electrons, and has two energy levels which means it occupies period two of the periodic table, and group two of the periodic table.
Barium (Ba) on the other had, has an atomic number of 56, which means it has 56 protons and 56 electrons. Thus it has an electron configuration of; 2;8;18;18;8;2; this shows that it has 6 energy levels thus occupies period 6 and is in group two since it has two valence electrons.

The atomic number of beryllium (Be) is 4, and the atomic number of barium (Ba) is 56. the comparison is best supported by this information is that beryllium has a lower atomic radius than Barium

Variations to the forehand stroke are not allowed. a. true b. false

Answers

This is b. false

There are numerous ways of adjusting the forehand stroke and variations are allowed.

Answer:

false

Explanation:

The forehand stroke is a basic shot in tennis, variations are allowed in order to boost performance (power, topspin and accuracy) of the player. Some guidelines to choose the correct forehand stroke are to visualize the correct stroke, position correctly, correct footwork and selecting shot location.

What is the definition of uniform motion?

Answers

Uniform motion means no part of the motion is changing.

The two parts of motion are . . . speed and direction.

If neither part is changing, that means constant speed in a straight line.

If a wave hits a smooth surface at an angle of incidence of 40 degrees, the angle of reflection is A. 40 degrees.
B. 0 degrees.
C. 90 degrees.
D. 80 degrees.

Answers

the angle of incidence is equal to the angle of reflection. If a wave hits a smooth surface at an angle of incidence of 40 degrees then the angle of reflection is 40 degrees.

D. 80 degrees.

The part of the ear where sound wave compressions and rarefactions cause the eardrum to vibrate is the middle ear. The 8th nerve in the inner ear actually converts the mechanical energy to electrical energy for transmitting to the brain. A membrane called the tympanic membrane separates the middle ear from the outer ear. Whenever a sound reaches the ear, it creates a sound wave that creates vibration in the eardrum. The pressure when high pushes the membrane inwards while low pressure sound waves helps the eardrum to come outwards.

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