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3 years ago

8

Tech A says quartz crystals under mechanical stress will produce a voltage. Tech B says the piezoelectric principle is used in c

oolant temp sensors. Who is correct?

1 answer:

pshichka [43]3 years ago

3 0

Answer:

Tech A is right.

Explanation:

Its the ability of quartz crystal that if we apply a mechanical stress on them by an applied force then they can produce the electricity or voltage. This phenomenon of producing electricity by squeezing a crystal is termed as piezoelectricity or a piezoelectric effect.

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What is it called when matter changes directly from a solid to a gas?

padilas [110]

Sublimation-is the transitional phase of solid to gas skipping the liquid phase entirely

5 0

3 years ago

A boat crossing a 153.0 m wide river is directed so that it will cross the river as quickly as possible. The boat has a speed of

Lynna [10]

We have the relation

$\vec v_{B \mid E} = \vec v_{B \mid R} + \vec v_{R \mid E}$

where $v_{A \mid B}$ denotes the velocity of a body A relative to another body B; here I use B for boat, E for Earth, and R for river.

We're given speeds

$v_{B \mid R} = 5.10 \dfrac{\rm m}{\rm s}$

$v_{R \mid E} = 3.70 \dfrac{\rm m}{\rm s}$

Let's assume the river flows South-to-North, so that

$\vec v_{R \mid E} = v_{R \mid E} \, \vec\jmath$

and let $-90^\circ < \theta < 90^\circ$ be the angle made by the boat relative to East (i.e. -90° corresponds to due South, 0° to due East, and +90° to due North), so that

$\vec v_{B \mid R} = v_{B \mid R} \left(\cos(\theta) \,\vec\imath + \sin(\theta) \, \vec\jmath\right)$

Then the velocity of the boat relative to the Earth is

$\vec v_{B\mid E} = v_{B \mid R} \cos(\theta) \, \vec\imath + \left(v_{B \mid R} \sin(\theta) + v_{R \mid E}\right) \,\vec\jmath$

The crossing is 153.0 m wide, so that for some time $t$ we have

$153.0\,\mathrm m = v_{B\mid R} \cos(\theta) t \implies t = \dfrac{153.0\,\rm m}{\left(5.10\frac{\rm m}{\rm s}\right) \cos(\theta)} = 30.0 \sec(\theta) \, \mathrm s$

which is minimized when $\theta=0^\circ$ so the crossing takes the minimum 30.0 s when the boat is pointing due East.

It follows that

$\vec v_{B \mid E} = v_{B \mid R} \,\vec\imath + \vec v_{R \mid E} \,\vec\jmath \\\\ \implies v_{B \mid E} = \sqrt{\left(5.10\dfrac{\rm m}{\rm s}\right)^2 + \left(3.70\dfrac{\rm m}{\rm s}\right)^2} \approx 6.30 \dfrac{\rm m}{\rm s}$

The boat's position $\vec x$ at time $t$ is

$\vec x = \vec v_{B\mid E} t$

so that after 30.0 s, the boat's final position on the other side of the river is

$\vec x(30.0\,\mathrm s) = (153\,\mathrm m) \,\vec\imath + (111\,\mathrm m)\,\vec\jmath$

and the boat would have traveled a total distance of

$\|\vec x(30.0\,\mathrm s)\| = \sqrt{(153\,\mathrm m)^2 + (111\,\mathrm m)^2} \approx \boxed{189\,\mathrm m}$

3 0

2 years ago

The dragster has a mass of 1.3 Mg and a center of mass at G. A parachute is attached at C provides a horizontal braking force of

adell [148]

Answer:

The deceleration of the dragster upon releasing the parachute such that the wheels at B are on the verge of leaving the ground is 16.33 m/s²

Explanation:

The additional information to the question is embedded in the diagram attached below:

The height between the dragster and ground is considered to be 0.35 m since is not given ; thus in addition win 0.75 m between the dragster and the parachute; we have: (0.75 + 0.35) m = 1.1 m

Balancing the equilibrium about point A;

F(1.1) - mg (1.25) = $ma_a (0.35)$

$1.8v^2(1.1)$ - 1200(9.8)(1.25) = 1200a(0.35)

$1.8v^2(1.1)$ - 14700 = 420 a ------- equation (1)

$F_x = ma_x \\ \\ = 1.8v^2 = 1200 \ a$ --------- equation (2)

Replacing equation 2 into equation 1 ; we have :

${1.1 * 1200 \ a} - 14700 = 420 a$

1320 a - 14700 = 420 a

1320 a - 420 a =14700

900 a = 14700

a = 14700/900

a = 16.33 m/s²

The deceleration of the dragster upon releasing the parachute such that the wheels at B are on the verge of leaving the ground is 16.33 m/s²

5 0

3 years ago

Two groups of students made plans to help their community during a hurricane. The first group suggested training the community a

zysi [14]

The correct option is D.
During hurricane, the most important thing is to get people out to safety in order to save their lives. Training the community about safety evacuation route is by far the better idea because it provide immediate safety from the natural hazard. The second idea is not a good one at all, because if food are stocked in every house in the community, the food will be destroyed alongside other things during the hurricane.

8 0

3 years ago

The drawing shows four sheets of polarizing material, each with its transmission axis oriented differently. Light that is polari

storchak [24]

Answer:

Explanation:

At the point when light is vertically polarized is incident on the polarizer whose axes are situated at angle points $\theta _1 , \theta _2 , \theta _3$ the intensity power in the wake of going through all the polarisers is given by the Malus law, applied threefold for every one of the three axes.

$I = I_o \ cos \theta _1 \ cos \theta _2 \ cos \theta _ 3$

The heading of the direction of the polarization is equivalent to the pivoted axes of the polarizer provided that light is an electromagnetic wave, its course of polarization is therefore controlled by the electric field part.

∴

a)

When sheet A is removed, the transmitted light goes through B, at 30°.

$I = I_o \ cos ^2 \theta _1 \ cos ^2 \theta _2 \ cos^2 \theta _3$

$I = 20 \ cos ^2 30 \ cos ^2 60 \ cos ^2 30$

$I = 2.81 \ W/m^2$

b)

When B is removed, No light passes since the axis of A and the axis of C are perpendicular to each other.

c)

When C is removed, the intensity is indeed zero since the axes are aligned and adjusted at 90° to one another.

$\mathbf{d) \ I - I_o cos^2 (0) cos^2 (30) \ cos^2 (60)}$

$\mathbf{d = 3.75 \ W/m^2}$

3 0

3 years ago