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3 years ago

True or false? All waves need a medium in order to travel

2 answers:

4 0

That's false. Mechanical waves (like sound and ocean waves) do
need a medium to travel in, but electromagnetic waves (like radio
and light) don't.

Pavlova-9 [17]3 years ago

3 0

That is false because electromagnetic waves can travel without a medium.

hope this helps :)

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If the net force acting on an object is zero, its inertia is also zero.<br> True or false

S_A_V [24]

Answer:

its false

Explanation:

5 0

3 years ago

A life preserver is thrown from an helicopter straight down to a person in distress. The initial velocity of the life preserver

Leno4ka [110]

Answer:29.627 m

Explanation:

Given

Initial velocity of life preserver(u) is 1.6 m/s

it takes 2.3 s to reach the water

using equation of motion

v=u+at

$v=1.6+9.81\times 2.3$

v=24.163 m/s

Let s be the height of life preserver

$v^2-u^2=2gs$

$24.163^2-1.6^2=2\times 9.81\times s$

$s=\frac{581.29}{2\times 9.81}$

s=29.627 m

6 0

3 years ago

The light reactions of photosynthesis supply the calvin cycle with __________.

Margaret [11]

Answer:

ATP and NADPH

Explanation:

4 0

3 years ago

Find the wavelength in meters for a transverse mechanical wave with an amplitude of 10 cm and a radian frequency of 20π rad/s if

nydimaria [60]

Answer:

The wavelength of the wave is 20 m.

Explanation:

Given that,

Amplitude = 10 cm

Radial frequency $\omega = 20\pi\ rad/s$

Bulk modulus = 40 MPa

Density = 1000 kg/m³

We need to calculate the velocity of the wave in the medium

Using formula of velocity

$v=\sqrt{\dfrac{k}{\rho}}$

Put the value into the formula

$v=\sqrt{\dfrac{40\times10^{6}}{10^3}}$

$v=200\ m/s$

We need to calculate the wavelength

Using formula of wavelength

$\lambda =\dfrac{v}{f}$

$\lambda=\dfrac{v\times2\pi}{\omega}$

Put the value into the formula

$\lambda=\dfrac{200\times2\pi}{20\pi}$

$\lambda=20\ m$

Hence, The wavelength of the wave is 20 m.

5 0

3 years ago

A sphere of radius R contains charge Q spread uniformly throughout its volume. Find an expression for the electrostatic energy c

tensa zangetsu [6.8K]

Answer:

$E = \frac{3kQ^2}{5R}$

Explanation:

Let the sphere is uniformly charge to radius "r" and due to this charged sphere the electric potential on its surface is given as

$V = \frac{kq}{r}$

now we can say that

$q = \frac{Q}{\frac{4}{3}\pi R^3} (\frac{4}{3}\pi r^3)$

$q = \frac{Qr^3}{R^3}$

now electric potential is given as

$V = \frac{k\frac{Qr^3}{R^3}}{r}$

$V = \frac{kQr^2}{R^3}$

now work done to bring a small charge from infinite to the surface of this sphere is given as

$dW = V dq$

$dW = \frac{kQr^2}{R^3} dq$

here we know that

$dq = \frac{3Qr^2dr}{R^3}$

now the total energy of the sphere is given as

$E = \int dW$

$E = \int_0^R \frac{kQr^2}{R^3} (\frac{3Qr^2dr}{R^3})$

$E = \frac{3kQ^2}{R^6} (\frac{R^5}{5} - 0)$

$E = \frac{3kQ^2}{5R}$

7 0

3 years ago