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3 years ago

6

Ocean waves are examples of:

1 answer:

astra-53 [7]3 years ago

8 0

B). longitudinal waves

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Why can't we currently power spacecraft beyond Jupiter on solar power?

iVinArrow [24]

Answer:

Ok, the answer is because there will not be enough sunlight for a spacecraft to power all the way.

3 0

4 years ago

During most of its lifetime, s star maintains an equilibrium size in which the inward force of gravity on each atom is balanced

frez [133]

Answer:

$r_f=137493m$

$v=8638940m/s$

Explanation:

During this process the mass $M=2\times10^{30}Kg$ will be considered constant. We start from a radius $r_i=7\times10^8m$ and a period $T_i=30\ days=(30)(24)(60)(60)s=2592000s$ . The final period is $T_f=0.1s$ .

Angular momentum <em>L</em> is conserved in this process. We can use the formula $L=I\omega$ , where I is the momentum of inertia (which for a solid sphere is $I=\frac{2mr^2}{5}$ ) and $\omega=\frac{2\pi }{T}$ is the angular velocity, so we can write the star's angular momentum as:

$L=I\omega=\frac{2mr^2}{5}\frac{2\pi }{T}=\frac{4\pi mr^2 }{5T}$

Since $L_f=L_i$ we have:

$\frac{4\pi mr_f^2 }{5T_f}=\frac{4\pi mr_i^2 }{5T_i}$

Which can be simplified as:

$\frac{r_f^2 }{T_f}=\frac{r_i^2 }{T_i}$

Which means:

$r_f=\sqrt{\frac{r_i^2 T_f}{T_i}}=r_i \sqrt{\frac{T_f}{T_i}}$

Which for our values is:

$r_f=r_i \sqrt{\frac{T_f}{T_i}}=(7\times10^8m) \sqrt{\frac{0.1s}{2592000s}}=137493m$

And we calculate the speed of a point on the equator by dividing the final circumference over the final period:

$v=\frac{C_f}{T_f}=\frac{2\pi r_f}{T_f}=\frac{2\pi (137493m)}{(0.1s)}=8638940m/s$

3 0

4 years ago

A student has to work the following problem: A block is being pulled along at constant speed on a horizontal surface a distance

brilliants [131]

Answer:

D

The answer cannot be found until it is known whether q is greater than, less than, or equal to 45°.

Explanation:

Since block moves with constant speed

So, frictional force

f = FCosq

Work done by friction

W = - fd

W = - fd Cos q

The answer may be greater or less than - fdSinq. It depends on the value of q which is less than, or equal to 45°.

6 0

3 years ago

Kids are pelting a window with snowballs. On average, two snowballs of roughly 300-g mass hit the window each second, moving hor

hram777 [196]

Answer:

The average force exerted on the window due to two snowballs is 6 N

Explanation:

Given:

Mass of snowballs $m = 300 \times 10^{-3}$ Kg

Velocity of snowball $v = 10 \frac{m}{s}$

For finding the average force,

Force is equal to the change in momentum,

$F = \frac{dP}{dt}$

Here, final velocity is zero so we write,

$F = \frac{mv}{1}$

Where $dt = 1$ sec

$F = 300 \times 10^{-30} \times 10$

$F = 3$ N

Above value of force is due to one ball, but here given in question there are two ball,

$F = 3 \times 2$

$F = 6$ N

Therefore, the average force exerted on the window due to two snowballs is 6 N

5 0

4 years ago

Which of the following is the equivalent resistance of the circuit shown?

erica [24]

I believe the answer is going to B I hope this helps and good luck

6 0

3 years ago