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Crazy boy [7]
3 years ago
13

Four engineers propose designs for door locks that are triggered by a sample of

Physics
1 answer:
sveta [45]3 years ago
7 0

Question:

A. Engineer A: "When the sample alpha decays, it will give off alpha particles. These will

trigger a photosensor (a device that senses forms of light) that will open the lock."

B. Engineer B: "When the sample alpha decays, it only releases large amounts of heat.

This will trigger a thermometer that will open the lock."

C. Engineer C: "When the sample alpha decays, it will lose mass, This will trigger a scale

that will open the lock."

D. Engineer D: "When the sample alpha decays, it will give off negatively charged alpha

particles. Because alpha particles are electrons, they will complete a circuit that will

open the lock."

Answer:

The correct option is;

A. Engineer A: "When the sample alpha decays, it will give off alpha particles. These will trigger a photosensor ( a device that senses forms of light) that will open the lock"

Explanation:

Here, we note that in alpha decay (α-decay) there is an emission of an alpha particle or helium nucleus with the transformation of the parent element nucleus into that of a different element, having reduced mass and atomic numbers

Alpha particles are a form of ionizing radiation with a mass of 6.64 × 10⁻²⁷ kg and therefore they can be sensed by a photo sensor but will be slowly sensed by a scale.

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A 0.130 m radius, 485-turn coil is rotated one-fourth of a revolution in 4.17 ms, originally having its plane perpendicular to a
Lady_Fox [76]

Answer:

The magnetic field strength needed is 1.619 T

Explanation:

Given;

Number of turns, N = 485-turn

Radius of coil, r = 0.130 m

time of revolution, t =  4.17 ms = 0.00417 s

average induced emf, V = 10,000 V.

Average induced emf is given as;

V = -ΔФ/Δt

where;

ΔФ is change in flux

Δt is change in time

ΔФ = -NBA(Cos \theta_f - Cos \theta_i)

where;

N is the number of turns

B is the magnetic field strength

A is the area of the coil = πr²

θ is the angle of inclination of the coil and the magnetic field,

\theta_f = 90^o\\\theta_i = 0^o

V = NBACos0/t

V = NBA/t

B = (Vt)/NA

B = (10,000 x 0.00417) / (485 x π x 0.13²)

B =1.619 T

Thus, the magnetic field strength needed is 1.619 T

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3 years ago
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Development of the Grand Canyon through the uplift of the plateau and erosion by the Colorado River illustrates that:
MAXImum [283]
Landforms result from a combination constructive and destructive forces.
Hope this helps
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3 years ago
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There are 2.2 pounds in a kilogram. if a boys mass is 40kg, what is his height in pounds?
sasho [114]
The simplest way to do this is to set up equivalent fractions, like this- 

\frac{1}{2.2} = \frac{40}{x}

Solve for x by using cross multiplication.

40*2.2= 88
1*x=88
x=88

Therefore, the boy weighs 88lbs. 
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3 years ago
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A batter hits a baseball with a bat. The bat exerts a force on the ball. Does the ball exert a force on the bat?
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4 years ago
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Which of the following is not an indication of a chemical reaction? a substance dissolves formation of a precipitate color chang
SVETLANKA909090 [29]

a substance dissolves.  


like adding a soluble salt to water, it just dissolves, i.e dissociates homogeneously as water is able to dissociate salts (ionic compounds) into its ions. (it can also dissociate other non-ionic compounds like HCL)  


the salt still remains chemically as a salt and is unchanged chemically thus it is not an indication of a chemical reaction as no chemical reaction has taken place.  


the formation of a precipitate is a chemical reaction because a new substance (i.e new chemical) is formed. For example adding aqueous sodium hydroxide into an aqueous solution with CU2+ cations will form a blue precipitate (that is copper (II) hydroxide which is insoluble, hence it precipitates). Since a new chemical is formed, a chemical reaction has taken place and thus indicates a chemical reaction.  


color change... im not sure but usually a color change will only occur when a new substance is formed. Like iron corrodes (i.e rust) slowly in moist air to form hydrated iron (III) oxide that is rust. (brown color).  


usually adding a mixture to a mixture has little energy change, i.e little heat taken in by the reaction mixture or little heat given out by the reaction mixture. Whereas when a new substance is formed, there is usually noticeable energy change like the container gets colder or hotter (without heat being supplied of course). For example dissolving basic oxides into water releases energy ( more energy released than gained = exothermic reaction).  


i think that should be the answer... hope it helped :D

4 0
3 years ago
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