Please help with this

Explain why mess extinctions occur and why it make sense to measure geologic time between mass extinctions

Nastasia [14]

Mass extinction occur from natural disasters, such as a n asteroid hitting earth or a volcano errupting and spread ash everywhere.

It makes sense to measure geologic time between mass extinctions because after each mass extinction, there is almost no life left and the few left have to repopulate, which may lead way to new mutations and new varieties of plants and animals.
<span />

3 0

3 years ago

the inductive reactance of a 20.0-mh inductor at a certain frequency is 120 ω. what is the frequency in hz?

QveST [7]

The inductive reactance of a 20.0-mh inductor at a certain frequency is 120 ω. 955hz is the frequency in hz

In physics, frequency is the number of waves that pass a fixed point in a unit of time as well as the number of cycles or vibrations that a body in periodic motion experiences in a unit of time.

How frequently something occurs is what is meant by the word frequency. A person blinking their eyelids 47 times in a minute is an example of frequency. the quality or state of happening frequently.

Frequency is a numerical value that expresses how frequently a specific item appears in the supplied data set. Grouped frequency distribution and Ungrouped In physics, frequency is a numerical value that expresses how frequently a specific item appears in the supplied data set. Distribution are the two different types of frequency tables.

To learn more about frequency please visit brainly.com/question/5102661
#SPJ4

6 0

2 years ago

Read 2 more answers

What is the formula for acceleration? ( PLEASE HELP! ALSO IF YOU GET B IT'S WRONG BECAUSE I ALREADY PUT THAT AND IT WAS WRONG so

skad [1K]

Answer:

option A is correct

Explanation:

acceleration the time rate of change of velocity or speed so

a=Δv/t

Δv=vf-vi

Δv= final speed-initial speed

now a=final speed-initial speed/time

3 0

4 years ago

A trebuchet was a hurling machine built to attack the walls of a castle under siege. A large stone could be hurled against a wal

Studentka2010 [4]

(a) 18.9 m/s

The motion of the stone consists of two independent motions:

- A horizontal motion at constant speed

- A vertical motion with constant acceleration ( $g=9.8 m/s^2$ ) downward

We can calculate the components of the initial velocity of the stone as it is launched from the ground:

$u_x = v_0 cos \theta = (25.0)(cos 41.0^{\circ})=18.9 m/s\\u_y = v_0 sin \theta = (25.0)(sin 41.0^{\circ})=16.4 m/s$

The horizontal velocity remains constant, while the vertical velocity changes due to the acceleration along the vertical direction.

When the stone reaches the top of its parabolic path, the vertical velocity has became zero (because it is changing direction): so the speed of the stone is simply equal to the horizontal velocity, therefore

$v=18.9 m/s$

(b) 22.2 m/s

We can solve this part by analyzing the vertical motion only first. In fact, the vertical velocity at any height h during the motion is given by

$v_y^2 - u_y^2 = 2ah$ (1)

where

$u_y = 16.4 m/s$ is the initial vertical velocity

$v_y$ is the vertical velocity at height h

$a=g=-9.8 m/s^2$ is the acceleration due to gravity (negative because it is downward)

At the top of the parabolic path, $v_y = 0$ , so we can use the equation to find the maximum height

$h_{max} = \frac{-u_y^2}{2a}=\frac{-(16.4)^2}{2(-9.8)}=13.7 m$

So, at half of the maximum height,

$h = \frac{13.7}{2}=6.9 m$

And so we can use again eq(1) to find the vertical velocity at h = 6.9 m:

$v_y = \sqrt{u_y^2 + 2ah}=\sqrt{(16.4)^2+2(-9.8)(6.9)}=11.6 m/s$

And so, the speed of the stone at half of the maximum height is

$v=\sqrt{v_x^2+v_y^2}=\sqrt{18.9^2+11.6^2}=22.2 m/s$

(c) 17.4% faster

We said that the speed at the top of the trajectory (part a) is

$v_1 = 18.9 m/s$

while the speed at half of the maximum height (part b) is

$v_2 = 22.2 m/s$

So the difference is

$\Delta v = v_2 - v_2 = 22.2 - 18.9 = 3.3 m/s$

And so, in percentage,

$\frac{\Delta v}{v_1} \cdot 100 = \frac{3.3}{18.9}\cdot 100=17.4\%$

So, the stone in part (b) is moving 17.4% faster than in part (a).

4 0

4 years ago

Can someone explain with the Answers pls?

Dovator [93]

Answer:

a) The frequency of the third harmonic is 786 Hz

b) The frequency of the first harmonic is 340 Hz

c) The frequency of the fifth harmonic is 1640 Hz

Explanation:

The rule is as follows:

If the first harmonic frequency (also called the fundamental frequency) is F, then:

The frequency of the second harmonic (also called the second overtone) is:

2*F

The frequency of the third harmonic (also called the third overtone) is:

3*F

And so on.

With this information, we can answer the questions:

a) We want to find the frequency of the third harmonic, such that the frequency of the first harmonic is 262 Hz.

Then we have F = 262Hz

And the frequency of the third harmonic will be:

3*F = 3*262Hz = 786 Hz

b) First harmonic for a string whose fifth harmonic frequency is 1700Hz.

Let's define F as the first frequency (the one we want to find)

Then the fifth harmonic frequency can be written as:

5*F = 1700Hz

With this equation we can find the value of F:

F = 1700Hz/5 = 340Hz

c) We want to find the fifth harmonic for a string whose third overtone (this is the same as the third harmonic) frequency is 984 Hz.

Then if the frequency of the first harmonic is F, we know that:

3*F = 984 Hz

With this we can find the value of F:

F = 984 Hz/3 =328 Hz

Now that we know the frequency of the first harmonic, we can find the frequency of the fifth harmonic:

5*F = 5*328 Hz = 1640 Hz

8 0

3 years ago