What kind of friction occurs as a fish swims through water?

PLEASE HELP!! IM TIMED!! WILL MARK BRAINLIEST!! 13 POINTS!! SCIENCE!!

Elena L [17]

C nuclear reactions involving the fusion of atoms occur in the core of a stars

5 0

3 years ago

A block pushed along the floor with velocity v0xv0x slides a distance dd after the pushing force is removed. If the mass of the

Volgvan

Answer:

There is no change in distance

Explanation:

Given that block slides a distance dd with initial velocity $v_{ox}$ $v_{ox}$

Work energy theorem states that Work done W is the difference between final kinetic energy $KE_{f}$ and initial kinetic energy $KE_{i}$

W = $KE_{f}$ - $KE_{i}$ ...........(equation 1)

In the given problem, the work is done by frictional force

Hence the work done is given by

$W_{Friction}$ = - $F_{Friction}$ x dd

$F_{Friction}$ is negative since it is resistive force and dd is the distance

$W_{Friction}$ = - μ mg X dd

where μ is coefficient of friction.

Also we know that Kinetic energy KE = $\frac{1}{2}$ $mv^{2}$

$KE_{f}$ = 0 since final velocity is zero

$KE_{i}$ = $\frac{1}{2}$ $m(v_{ox} v_{ox}) ^{2}$

Substituting the corresponding values equation 1 becomes

-μ mg x dd = 0 - $\frac{1}{2}$ $m(v_{ox} v_{ox}) ^{2}$

dd= $\frac{(v_{ox}v_{ox} )^{2} }{2g}$ x (1/μ) ........... (equation 2)

To find distance when mass of block is doubled and initial velocity is not changed:

Equation 2 shows that the distance dd is independent of mass, therefore there is no change in distance.

5 0

3 years ago

Unless indicated otherwise, assume the speed of sound in air to be v = 344 m/s.A violinist is tuning her instrument to concert A

Molodets [167]

Answer:

A) 443 Hz

B) She has to loosen the string

Explanation:

A) Given;

Beat frequency;f_beat = 3 Hz

Frequency of electronically generated tone; f_e = 440 Hz

We know that formula for beat frequency is given by;

f_beat = |f1 - f2|

Now, applying it to this question, we have;

f_beat = f_v - f_e

Where f_v is frequency of the note played by the violinist

Thus, plugging in the relevant values;

3 = f_v - 440

f_v = 3 + 440

f_v = 443 Hz

B) In the concept of wave travelling in a string, the frequency is directly proportional to the square root of the force acting on the string.

Now, for the violinist to get her violin perfectly tuned to concert A from what it was when she heard the 3-Hz beats, the beat frequency will have to be zero. Which means it has to decrease by 3 Hz. For it to decrease, it means that the force applied has to decrease as we have seen that frequency is directly proportional to the square root of the force acting on the string.

Thus, she would have to loosen the string.

7 0

4 years ago

During a certain time interval, the angular position of a swinging door is described by θ = 4.91 + 9.7t + 2.06t2, where θ is in

polet [3.4K]

Explanation:

a)

θ = 4.91 + 9.7t + 2.06t² when t = 0

θ = 4.91 rad

θ = 4.91 + 9.7t + 2.06t²

ω = dθ/dt = 9.7 + 2.06t, when t =0

ω = dθ/dt = 9.7 + 0

ω = 9.7 rad/s

α = d²θ/dt² = 2.06

α= 2.06 rad/s²

b) please use same method above for t = 2.94 s

3 0

3 years ago

In the Zeeman effect, the energy levels of hydrogen are split by a magnetic field. Each state with a different value of mlml has

Nikolay [14]

Answer:

the Zeeman effect without spin is three lines

Explanation:

The Zeeman effect is the result of the interaction of the magnetic field with the orbital angular momentum of the electrons, if we do not take the spin into account it is called the Normal Zeeman effect.

Therefore we only take into account the orbital moments (m_l) of the transition, from the selection rules of the refreshed harmonics, only the transition with

$\Delta m_l$ = 0, ± 1

ΔE $\DeltaE = \mu_B \ \Delta m_l \ B$

Let's analyze for the case of the Hydrogen atom

For a transition between levels n = 1 and n = 2 the values of m_l are n_f = 1 m_l = 0 and for n₀ = 2 m_l = 0, 1

so we only have two lines.

For transition n_f = 2 and n₀ = 3

n_f = 2 m_l = 0, 1

n₀ = 3 m_l = -1, 0, 1

There are only two lines plus the central line, so there are three spectral lines

for n_f = 3 and n_o = 4

n_f = 3 ml = -1, 0, 1

n₀= 4 ml = -2, -1, 0, 1, 2

Only transitions with Δm_l = ±1 are allowed, so there are only two transitions plus the central transition (Δm_l = 0), so there are only 3 spectral lines.

In summary, due to the selection rule of spherical harmonics, the greatest number of lines in the Zeeman effect without spin is three lines.

3 0

3 years ago