Which of the following statements are true about magnets?

A boat is subject to hydrodynamic drag forces of F = 40v 2 [N] where v is the magnitude of velocity in [m/s]. The boat’s mass is

stepladder [879]

Answer:

It has moved a distance, S = 25.9 m

Explanation:

F = 40 v²........(1)

$F = mv\frac{dv}{dS}$ .........(2)

Equating (1) and (2)

$-mv\frac{dv}{dS} = 40 v^2\\\\v\frac{dv}{dS} = \frac{-40 v^2}{m} \\\\m = 450 kg\\v\frac{dv}{dS} = \frac{-40 v^2}{450}\\\\ \frac{dv}{v} = \frac{40}{450} dS\\$

Integrate both sides:

$v_1 = 1, v_2 = 10$

$\int\limits^{10}_1 {\frac{1}{v} } \, dv = \frac{-40}{450} \int\limits^S_0 \, dS \\\\ln\frac{1}{10} = \frac{-40}{450} (S-0)\\\\S = \frac{-40}{450} ln(0.1)\\\\S = 25.9 m$ .

6 0

3 years ago

Two sound waves, from two different sources with the same frequency, 540 Hz, travel in the same direction at 330 m s . The sourc

oee [108]

Answer:

The value is $\Delta \phi = 4.12 \ rad$

Explanation:

From the question we are told that

The frequency of each sound is $f_1 = f_2 = f = 540 \ Hz$

The speed of the sounds is $v = 330 \ m/s$

The distance of the first source from the point considered is $a = 4.40 \ m$

The distance of the second source from the point considered is $b = 4.00 \ m$

Generally the phase angle made by the first sound wave at the considered point is mathematically represented as

$\phi_a = 2 \pi [\frac{a}{\lambda} + ft]$

Generally the phase angle made by the first sound wave at the considered point is mathematically represented as

$\phi_b = 2 \pi [\frac{b}{\lambda} + ft]$

Here b is the distance o f the first wave from the considered point

Gnerally the phase diffencence is mathematically represented as

$\Delta \phi= \phi_a - \phi_b = 2 \pi [\frac{ a}{\lambda} + ft ] - 2 \pi [\frac{b}{\lambda} + ft ]$

=> $\Delta \phi = \frac{2\pi [ a - b]}{ \lambda }$

Gnerally the wavelength is mathematically represented as

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

=> $\lambda = \frac{330}{540}$

=> $\lambda = 0.611 \ m$

=> $\Delta \phi = \frac{2* 3.142 [ 4.40 - 4.0 ]}{ 0.611 }$

=> $\Delta \phi = 4.12 \ rad$

5 0

3 years ago

What property do the following elements have in common? Li, C, and F A) They are poor conductors of electricity. B) Each element

Aloiza [94]

Answer: Option (D) is the correct answer.

Explanation:

The given elements Li, C and F are all second period elements. So, when we move from left to right across a period then there occurs increase in number of valence electrons as there occurs increase in total number of electrons.

So, it means more electrons are added to the same energy level.

Thus, we can conclude that a property of valence electrons for each element is located in the same energy level is common in the given elements.

7 0

3 years ago

Read 2 more answers

What is the kinetic energy of a 2000 kg car moving at 72 km/h?

gtnhenbr [62]

kinetic energy is given by 1 /2

$\times mass \: \times \: velocity {?}^{2}$ then you have to replace the figures