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2 years ago

How many neutrons does element X have if its atomic number is 26 and its mass number is 82?

Physics

1 answer:

taurus [48]2 years ago

6 0

The mass number is calculated by adding the number of protons and the number of neutrons.

Therefore, you can find the number of neutrons by subtracting the number of protons from the mass number. The number of protons is equal to the atomic number, therefore you just have to do the mass number - atomic number to find the number of neutrons.

82 - 26 = 56 neutrons.

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HELP ASAP VERY IMPORTANT.

sertanlavr [38]

Answers:

1. The hot soup will loose the heat and the ice water will gain the heat

If two jars are insulated inside the insulated box, the heat may not be transferred to outside of the box.

According to II law of thermodynamics, Heat always flow from high temperature body to low temperature body, with out aid of external energy.

So, from two points, it is concluded that The hot soup will lose heat and the ice water will gain the heat until they reach the thermodynamic equilibrium.

2. The particles in gases are farther apart and move faster

Particles in the gases are loosely packed (greater distance between particles compared to solids and liquids) and particles collide less often.

Therefore conduction is weak in gases compared to solids and liquids.

3. Heat and milk by conduction; popping popcorn by radiation.

The heat can transfer from pot to the milk by conduction because they are in contact at boundaries, similarly the pot and the stove are in contact so the conduction transfers heat from pot to the milk. 
In microwave oven there is no direct contact (no conduction) of heat and popcorn, also there is no molecular momentum transfer (means of no convection).

So obviously the heat transfer by radiation occurs in a microwave oven.

4 0

2 years ago

A certain spring exerts a nonlinear force given by F(x) = −60x − 18x2 , where x is in meters and F is in newtons. A 0.90-kg bloc

tia_tia [17]

Answer:

a) W = 6.75 J and b) v = 3.87 m / s

Explanation:

a) In the problem the force is nonlinear and they ask us for work, so we must use it's definition

W = ∫ F. dx

Bold indicates vectors. In a spring the force is applied in the direction of movement, whereby the scalar product is reduced to the ordinary product

W = ∫ F dx

We replace and integrate

W = ∫ (-60 x - 18 x²) dx

W = -60 x²/2 -18 x³/3

Let's evaluate between the integration limits, lower W = 0 for x = -0.50 m, to the upper limit W = W for x = 0 m

W = -30 [0- (-0.50) 2] -6 [0 - (- 0.50) 3]

W = 7.5 - 0.75

W = 6.75 J

b) Work is equal to the variation of kinetic energy

W = ΔK

W = ΔK = ½ m v² -0

v =√ 2W/m

v = √(2 6.75/ 0.90)

v = 3.87 m / s

8 0

3 years ago

An ice skater of mass m = 60 kg coasts at a speed of v = 0.8 m/s past a pole. At the distance of closest approach, her center of

IrinaVladis [17]

Answer:

1.78 rad/s

1.70344 rad/s

Explanation:

v = Velocity = 0.8 m/s

m = Mass of person = 60 kg

$r_1$ = Distance between center of mass of person and pole = 0.45 m

$r_2$ = New distance between center of mass of person and pole = 0.46 m

I = Moment of inertia

Angular speed is given by

$\omega_1=\dfrac{v}{r_1}\\\Rightarrow \omega_1=\dfrac{0.8}{0.45}\\\Rightarrow \omega_1=1.78\ rad/s$

The angular speed is 1.78 rad/s

In this system the angular momentum is conserved

$L_1=L_2\\\Rightarrow I_1\omega_1=I_2\omega_2\\\Rightarrow mr_1^2\omega_1=mr_2^2\omega_2\\\Rightarrow \omega_2=\dfrac{r_1^2\omega_1}{r_2^2}\\\Rightarrow \omega_2=\dfrac{0.45^2\times 1.78}{0.46^2}\\\Rightarrow \omega_2=1.70344\ rad/s$