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2 years ago

Someone Help me please

Physics

1 answer:

natali 33 [55]2 years ago

7 0

Answer:

a) Yes because spiderman isn’t part of the system (the train), so he exerts an external force on the system, causing it to slow. The sign is negative because the train is slowing negative.

b) The train was initially moving, so it had kinetic energy, the energy of movement. There isn’t the same amount anymore because spiderman did work onto the train. Work is defined by the change of kinetic energy of the system, so the train didn’t have the same amount of that type of energy at the end.

I hope this helps! :)

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An ore sample weighs 17.50 N in air. When the sample is suspended by a light cord and totally immersed in water, the tension in

valkas [14]

Answer:

Volume of the sample: approximately $\rm 0.6422 \; L = 6.422 \times 10^{-4} \; m^{3}$ .

Average density of the sample: approximately $\rm 2.77\; g \cdot cm^{3} = 2.778 \times 10^{3}\; kg \cdot m^{3}$ .

Assumption:

$\rm g = 9.81\; N \cdot kg^{-1}$ .
$\rho(\text{water}) = \rm 1.000\times 10^{3}\; kg \cdot m^{-3}$ .
Volume of the cord is negligible.

Explanation:

<h3>Total volume of the sample</h3>

The size of the buoyant force is equal to $\rm 17.50 - 11.20 = 6.30\; N$ .

That's also equal to the weight (weight, $m \cdot g$ ) of water that the object displaces. To find the mass of water displaced from its weight, divide weight with $g$ .

$\displaystyle m = \frac{m\cdot g}{g} = \rm \frac{6.30\; N}{9.81\; N \cdot kg^{-1}} \approx 0.642\; kg$ .

Assume that the density of water is $\rho(\text{water}) = \rm 1.000\times 10^{3}\; kg \cdot m^{-3}$ . To the volume of water displaced from its mass, divide mass with density $\rho(\text{water})$ .

$\displaystyle V(\text{water displaced}) = \frac{m}{\rho} = \rm \frac{0.642\; kg}{1.000\times 10^{3}\; kg \cdot m^{-3}} \approx 6.42201 \times 10^{-4}\; m^{3}$ .

Assume that the volume of the cord is negligible. Since the sample is fully-immersed in water, its volume should be the same as the volume of water it displaces.

$V(\text{sample}) = V(\text{water displaced}) \approx \rm 6.422\times 10^{-4}\; m^{3}$ .

<h3>Average Density of the sample</h3>

Average density is equal to mass over volume.

To find the mass of the sample from its weight, divide with $g$ .

$\displaystyle m = \frac{m \cdot g}{g} = \rm \frac{17.50\; N}{9.81\; N \cdot kg^{-1}} \approx 1.78389 \; kg$ .

The volume of the sample is found in the previous part.

Divide mass with volume to find the average density.

$\displaystyle \rho(\text{sample, average}) = \frac{m}{V} = \rm \frac{1.78389\; kg}{6.42201 \times 10^{-4}\; m^{3}} \approx 2.778\; kg \cdot m^{-3}$ .

3 0

3 years ago

What parameters affects the inductance of a coil

Kazeer [188]

Answer:

Number of Wire Turns in the Coil.

Explanation:

The greater the number of turns of wire in the coil, the greater the inductance. Fewer turns of wire in the coil results in lesser inductance. More coils of wires indicate a greater amount of magnetic field force for a given amount of coil current.

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2 years ago

The atomic mass of an element is defined as the weighted average mass of that element’s

marishachu [46]

Answer:

False

Explanation:

Atomic mass (Also called Atomic Weight, although this denomination is incorrect, since the mass is property of the body and the weight depends on the gravity) Mass of an atom corresponding to a certain chemical element). The uma (u) is usually used as a unit of measure. Where u.m.a are acronyms that mean "unit of atomic mass". This unit is also usually called Dalton (Da) in honor of the English chemist John Dalton.

It is equivalent to one twelfth of the mass of the nucleus of the most abundant isotope of carbon, carbon-12. It corresponds roughly to the mass of a proton (or a hydrogen atom). It is abbreviated as "uma", although it can also be found by its English acronym "amu" (Atomic Mass Unit). However, the recommended symbol is simply "u".

<u> The atomic masses of the chemical elements are usually calculated with the weighted average of the masses of the different isotopes of each element taking into account the relative abundance of each of them</u>, which explains the non-correspondence between the atomic mass in umas, of an element, and the number of nucleons that harbors the nucleus of its most common isotope.

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3 years ago

A substance with a pH of 9 has

Lady bird [3.3K]

A) no H30+ ions or OH- ions.

3 0

3 years ago

A machinist turns the power on to a grinding wheel, which is at rest at time t = 0.00 s. The wheel accelerates uniformly for 10

sashaice [31]

Answer:

Time interval;Δt ≈ 37 seconds

Explanation:

We are given;

Angular deceleration;α = -1.6 rad/s²

Initial angular velocity;ω_i = 59 rad/s

Final angular velocity;ω_f = 0 rad/s

Now, the formula to calculate the acceleration would be gotten from;

α = Change in angular velocity/time interval

Thus; α = Δω/Δt = (ω_f - ω_i)/Δt

So, α = (ω_f - ω_i)/Δt

Making Δt the subject, we have;

Δt = (ω_f - ω_i)/α

Plugging in the relevant values to obtain;

Δt = (0 - 59)/(-1.6)

Δt = -59/-1.6

Δt = 36.875 seconds ≈ 37 seconds

6 0

3 years ago