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aleksandrvk [35]

3 years ago

9

Which is true of a mechanical wave?

2 answers:

timurjin [86]3 years ago

5 0

A) It must have a medium.

nydimaria [60]3 years ago

5 0

A) True

Mechanical waves need a medium to travel.

B) False.

Mechanical waves need a medium to travel. So they can not travel in empty space.

C) False

Sound is a mechanical wave since it needs a medium to travel. light wave is electromagnetic wave and it can travel in empty space too.

D) False

Mechanical waves need a medium to travel. So they can not travel in empty space.

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A dielectric material, such as Teflon , is placed between the plates of a parallel-plate capacitor without altering the structur

Setler [38]

Answer:

1. The voltage decreases because of the insertion of the Teflon.

Explanation:

When we placed the dielectric medium/material between the plates of the capacitor. It increases the capacitance. Increase in capacitance means that the electric field between the plates will decrease and thus there will be a decrease in voltage. As we know that the capacitance has an inverse relation with the electric field between the plates. Mathematically,

$q = CV\\C = Q/V$

where C is capacitance, V is Voltage and q is a charge.

By putting "Teflon between the plates of capacitor there will be a decrease in voltage."

4 0

3 years ago

How can we fill ink inside a pen?

Tanya [424]

Answer:

Open the cap and fill the ink ...

As simple as me

Explanation:

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4 0

3 years ago

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A small electric motor produces a force of 5 N that moves a remote-control car 5 m every second. How much power does the motor p

kati45 [8]

Answer:

Explanation:

Given:

Force, f = 5 N

Velocity, v = 5 m/s

Power, p = energy/time

Energy = mass × acceleration × distance

Poer, p = force × velocity

= 5 × 5

= 25 W.

Note 1 watt = 0.00134 horsepower

But 25 watt,

0.00134 hp/1 watt × 25 watt

= 0.0335 hp.

4 0

3 years ago

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A student holds one end of a thread, which is wrapped around a cylindrical spool, as shown above. The student then drops the spo

lesya [120]

by energy conservation we know that

KE or rotation + KE of translation = gravitational PE

now we have

$\frac{1}{2}I\omega^2 + \frac{1}{2}mv^2 = mgH$

also we know that

$v = R\omega$

now we have

$\frac{1}{2}(\frac{1}{2}mR^2)\omega^2 + \frac{1}{2}m(R\omega)^2 = mgH$

$\frac{3}{4}mR^2\omega^2 = mgH$

$\omega = \sqrt{\frac{4gH}{3}}/R$

now when it is rolling on ground the torque acting on it due to friction force is given by

$\tau = R F_f$

$\tau = \mu mg R$

$\alpha = \frac{\mu mg R}{\frac{1}{2}mR^2}$

$\alpha = \frac{2 \mu g}{R}$

now angular speed at any time is given as

$\omega = \omega_i + \alpha t$

$\omega = \sqrt{\frac{4gH}{3}}/R -\frac{2 \mu g}{R} t$

so above is the angular speed in terms of time "t"

7 0

4 years ago

HELLO! Please Help me. <br>I can't do it! it's Science

inessss [21]

Answer:

9V

Explanation:

V=IR

V=2.5*3.6

V=9

4 0

3 years ago

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