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3 years ago

I don't understand how to do this. Its science by th way

Physics

1 answer:

Alex_Xolod [135]3 years ago

8 0

Answer:

the answer is Z,X,W,Y

Explanation:

we know Z is the hardest material because when it is rubbed against any material,the other material is definitely left with a mark,so Z is 1st

we know Y is the weakest material because when it is scratched by all other materials,it is left with a mark.so we write Y at the last.

X is rubbed against W and W is left with a mark,so we know that X is harder than W,so we should write X just before W and after Z.

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Two observers in different inertial reference frames moving relative to each other at nearly the speed of light see the same two

lions [1.4K]

Answer:

The correct answer is d Both the observer's are correct

Explanation:

We know by postulates of relativity that laws of physics are same in different inertial frames.

Thus for each of the frames they make observations related to their frames and since the observations are true for their individual frames they both are correct. But when we compare the two frames we need to use transformation equations to compare both the results.

3 0

3 years ago

4.72 A full-wave bridge-rectifier circuit with a 1-k load operates from a 120-V (rms) 60-Hz household supply through a 12-to-1 s

melisa1 [442]

Answer:

a) 12.74 V

b) Two pairs of diode will work only half of the cycle

c) 8.11 V

d) 8.11 mA

Explanation:

The voltage after the transformer is relationated with the transformer relationshinp:

$V_o=Vrms*\frac{1}{12}\\V_o=10Vrms$

the peak voltage before the bridge rectifier is given by:

$V_{op}=Vo*\sqrt{2}\\V_{op}=14.14V$

The diodes drop 0.7v, when we use a bridge rectifier only two diodes are working when the signal is positive and the other two when it's negative, so the peak voltage of the load is:

$V_l=V_{op}-2(0.7)\\V_l=12.74V$

As we said before only two diodes will work at a time, because the signal is half positive and half negative,so two of them will work only half of the cycle.

The averague voltage on a full wave rectifier is given by:

$V_{avg}=2*\frac{V_l}{\pi}\\V_{avg}=8.11V$

Using Ohm's law:

$I_{avg}=\frac{V_{avg}}{R}\\\\I_{avg}=8.11mA$

7 0

3 years ago

A small charged bead has a mass of 1.0 g. It is held in a uniform electric field of magnitude E = 200,000 N/C, directed upward.

Art [367]

Answer:

10^-7 C

Explanation:

m = 1 g = 10^-3 kg, E = 200,000 N/C, a = 20 m/s^2, u = 0

Let q be the charge on bead

Force = m a = q E

a = q E / m

q = m a / E = (10^-3 x 20) / 200000 = 10^-7 C

4 0

3 years ago

Find the ratio of the diameter of aluminium to copper wire, if they have the same

kicyunya [14]

Answer:

1.24

Explanation:

The resistivity of copper $\rho_1=2.65\times 10^{-8}\ \Omega-m$

The resistivity of Aluminum, $\rho_2=1.72\times 10^{-8}\ \Omega-m$

The wires have same resistance per unit length.

The resistance of a wire is given by :

$R=\rho \dfrac{l}{A}\\\\R=\rho \dfrac{l}{\pi (\dfrac{d}{2})^2}\\\\\dfrac{R}{l}=\rho \dfrac{1}{\pi (\dfrac{d}{2})^2}$

According to given condition,

$\rho_1 \dfrac{1}{\pi (\dfrac{d_1}{2})^2}=\rho_2 \dfrac{1}{\pi (\dfrac{d_2}{2})^2}\\\\\rho_1 \dfrac{1}{{d_1}^2}=\rho_2 \dfrac{1}{{d_2}^2}\\\\(\dfrac{d_2}{d_1})^2=\dfrac{\rho_1}{\rho_2}\\\\\dfrac{d_2}{d_1}=\sqrt{\dfrac{\rho_1}{\rho_2}}\\\\\dfrac{d_2}{d_1}=\sqrt{\dfrac{2.65\times 10^{-8}}{1.72\times 10^{-8}}}\\\\=1.24$

So, the required ratio of the diameter of Aluminum to Copper wire is 1.24.

3 0

3 years ago

Speed is the ratio of the distance an object moves to

guajiro [1.7K]

A - the amount of time needed to travel the distance

The formula for speed is distance/time and the unit is m/s. Therefore you divide the distance travelled by the time it took to travel it.

6 0

3 years ago

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I don't understand how to do this. Its science by th way​

I don't understand how to do this. Its science by th way