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3 years ago

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A mini rail gun made of a copper rod of mass m and radius r rests on two parallel copper rails that are a distance L apart and o

f length d. A magnetic field of magnitude B is directed perpendicular to the rod and the rails. When current is applied to the parallel copper rails, the rod rolls along the rails without slipping. If the rod starts from rest, what is the speed of the rod as it leaves the rails?

1 answer:

ira [324]3 years ago

7 0

Answer:

Explanation:

Magnetic Force on the rod F = Bi L

Work done by this force = F X d

= Bi Ld

This energy is converted into both rotational and linear kinetic energy

= 1/2 I ω² + 1/2 mv²

= 1/2 x 1/2 m r²ω²+ 1/2 mv²

= 1/4 m v² + 1/2 mv²

= 3/4 mv²

So according to conservation of energy

Bi Ld = 3/4 mv²

v = $\sqrt{\frac{4BiLd}{3m} }$

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Crystals are made using supersaturated solutions of solids in water.

labwork [276]

The way these supersaturated solutions are made is: A. The water would need to be heated to a higher temperature, which would give molecules and ions more kinetic energy, increasing solubility.

Solubility is simply a measure of how readily a substance is able to dissolve in a solvent to form a solution. Thus, a substance is soluble when it dissolves completely in a solvent and it is considered to be insoluble when it does not dissolve in a solvent or if it only dissolves partially.

A supersaturated solution can be defined as a solution that contains more solute than the equilibrium amount.

Generally, supersaturated solutions of solids in water are typically used for the creation of crystals because they are able to hold more of the solute than they would at room temperature.

In order to create these supersaturated solutions, the water should be heated to a higher temperature, so that the water molecules and ions can gain more kinetic energy and thereby increasing solubility.

In conclusion, heating the water to a higher temperature causes the water molecules and ions to gain more kinetic energy and thereby increasing solubility..

Read more: brainly.com/question/24058779

8 0

3 years ago

Read 2 more answers

The basic barometer can be used to measure the height of a building. If the barometric readings at the top and at the bottom of

Elan Coil [88]

Answer: 230.50 m

Explanation:

We have the following information:

$h_{Hg-TOP}=675mmHg=0.675m$ the barometric reading at the top of the building

$h_{Hg-BOT}=695mmHg=0.695m$ the barometric reading at the bottom of the building

$\rho _{air}=1.18 kg/m^{3}$ density of air

$\rho _{Hg}=13600 kg/m^{3}$ density of mercury

$g=9.8/m^{2}$ gravity

And we need to find the height of the building.

In order to approach this problem, we will firstly use the following equations to find the pressure at the top of the building $P_{TOP}$ and the perssure at the bottom $P_{BOT}$ :

$P_{TOP}=\rho _{Hg} g h_{Hg-TOP}$ (1)

$P_{BOT}=\rho _{Hg} g h_{Hg-BOT}$ (2)

From (1): $P_{TOP}=(13600 kg/m^{3})(9.8/m^{2})(0.675m)=89964 Pa$ (3)

From (2): $P_{BOT}=(13600 kg/m^{3})(9.8/m^{2})(0.695m)=92629.6 Pa$ (4)

Having the pressures at the top and the bottom of the building, we can calculate the variation in pressure $\Delta P$ :

$\Delta P=P_{BOT} - P_{TOP}$ (5)

$\Delta P=92629.6 Pa - 89964 Pa=2665.6 Pa$ (6)

On the other hand, we have a column of air with a cross-section area $A$ and the same height of the building, lets name it $h_{air}$ .

As pressure is defined as the force $F$ exerted on a specific area $A$ , we can write:

$\Delta P=\frac{F}{A}$ (7)

If we isolate $F$ we have:

$F= A \Delta P$ (8)

Also, the force gravity exerts on this column of air (its weight) is:

$F=m_{air} g$ (9)

Knowing the density of air is: $\rho_{air}=\frac{m_{air}}{V_{air}}$ (10)

where the volume of air can be written as: $V_{air}=(A)(h_{air})$ (11)

Substituting (1) in (10):

$\rho_{air}=\frac{m_{air}}{(A)(h_{air}}$ (12)

Isolating $m_{air}$ :

$m_{air}=(\rho_{air}) (A) (h_{air})$ (13)

Substituting (13) in (9):

$F=(\rho_{air}) (A) (h_{air}) (g)$ (14)

Matching (8) and (14)

$A \Delta P=(\rho_{air}) (A) (h_{air}) (g)$ (15)

Isolating $h_{air}$ :

$h_{air}=\frac{\Delta P}{g \rho_{air}}$ (16)

Substituting the known and calculated values:

$h_{air}=\frac{2665.6 Pa}{(9.8m/s^{2}) (1.18 kg/m^{3})}$ (17)

Finally:

$h_{air}=230.50 m$ This is the height of the building

8 0

3 years ago

Which of the following is a FALSE statement about acceleration? A. Acceleration can be zero, positive, or negative. B. An object

olchik [2.2K]

<h3><u>Answer</u>;</h3>

C. An object can have acceleration with negative velocity.

<h3><u>Explanation</u>;</h3>

Acceleration is a measure of the change in velocity over time. The change in velocity is measured in meter per second (m/s), and time interval is measured in second (s).
Therefore, acceleration measures the change in meters per second every second [(m/s)/s], namely meters per second per second or meters per second squared (m/s2).
If an object has zero acceleration, its velocity doesn’t have to be zero. Acceleration is a measure of the change in velocity over time. Zero acceleration means there is no change in velocity over time, namely constant velocity.

6 0

3 years ago

A tension force of 175 N inclined at 20.0° above the horizontal is used to pull a 40.0 - kg packing crate a distance of 6.00 m o

Murljashka [212]

Answer:

(a) Work done by the tension force is 987 J

(b) Coefficient of kinetic friction between the crate and surface is 0.495

Explanation:

(a)

Work done by any force F in moving an object by a distance d making an angle $\Theta$ with the direction of force is given by

$W=Fd\cos (\Theta )$

$W=175 \times 6 \times \cos (20 )J=987J$

Thus work done by the tension force is 987 J

(b)

Normal force on the crate is given by

$N= mg-F\sin \Theta =(40\times 9.8-175\times \sin 20)Newton$

=>N=332 Newtons

Since crate is moving with constant speed . Therefore using Newtons second law .

$Fcos(\Theta ) -\mu_k N=0$

Where $\mu_k$ =coefficient of kinetic friction

$\therefore \mu_k=\frac{F\cos (\Theta )}{N}$

=> $\mu_k=\frac{175\times \cos 20}{332}$

=> $\mu _k= 0.495$

Thus coefficient of kinetic friction between the crate and surface is 0.495

4 0

3 years ago

What is law of conservation of mass

timurjin [86]

Explanation:

<h2>law of conservation of mass</h2>

The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.

5 0

3 years ago