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4 years ago

Which of the following are possible causes of mass extinctions that scientists have identified

Physics

1 answer:

Alecsey [184]4 years ago

4 0

Answer:

over harvesting, pollution, introduction of invasive species such as new predators and food competitors

Explanation:

The main cause of mass extinction is Humans cause extinction of a species through overharvesting. The second main cause is pollution ., introduction of invasive species such as new predators and food competitors, habitat destruction, overhunting and other influences. Another very important cause of mass extinction is the unsustainable human population growth.

The five mass extinction events are

Ordovician Mass Extinction

Devonian Mass Extinction

Permian Mass Extinction

Triassic -Jurassic Mass Extinction

and Cretaceous -Tertiary (or the K-T) Mass Extinction.

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A straight wire carries a 12-A current eastward and a second straight wire carries a 14-A current westward. The wires are separa

USPshnik [31]

Answer:

$5.12\cdot 10^{-4} N$

Explanation:

The force exerted between two current-carrying wires is given by

$F=\frac{\mu_0 I_1 I_2 L}{2 \pi r}$

where

$\mu_0$ is the vacuum permeability

I1 and I2 are the two currents

L is the length of the segment of wire on which we want to calculate the force

r is the distance between the wires

In this problem we have:

$I_1 = 12 A\\I_2 = 14 A\\r = 42 cm = 0.42 m\\L = 6.4 m$

Substituting into the formula, we find:

$F=\frac{(4\pi \cdot 10^{-7})(12)(14)(6.4)}{2 \pi (0.42)}=5.12\cdot 10^{-4} N$

And since the direction of the two currents is opposite, the force between the wires is repulsive.

7 0

4 years ago

What are 5 wave interactions with matter?

liberstina [14]

Reflection
Refraction
Diffraction
Transmission
Absorption

8 0

3 years ago

2. The gravitational field intensity is measured in: a. N c. kg d. Nm2/kg? b. N/kg

alexdok [17]

Answer:

N/kg

Explanation:

newton/kilogram is the answer.please mark me brainliest

4 0

3 years ago

A 82-kg skydiver has a speed of 40 m/s at an altitude of 490 m above the ground. Calculate the total mechanical energy of the sk

Sav [38]

Answer:

$ME=459,364J$

Explanation:

Mechanical Energy=Potential Energy+ kinetic Energy

$m=82kg,g=9.8N/kg,h=490m,v=40m/s$

To calculate Kinetic Energy:-

$KE=\frac{1}[2}mv^2\\=\frac{1}{2}\times82kg \times(40m/s)^2\\=65600J$

To calculate Potential Energy:-

$PE=mgh\\=82kg \times9.8N/kg \times490\\=393764$

therefore,

$ME=KE+PE\\=65600+393764\\=459364J$

The skydiver's total mechanical energy is 459365J

8 0

3 years ago

When the magnetic flux through a single loop of wire increases by , an average current of 40 A is induced in the wire. Assuming

Zielflug [23.3K]

COMPLETE QUESTION:

When the magnetic flux through a single loop of wire increases by 30 Tm^2 , an average current of 40 A is induced in the wire. Assuming that the wire has a resistance of 2.5 ohms , (a) over what period of time did the flux increase? (b) If the current had been only 20 A, how long would the flux increase have taken?

Answer:

(a). The time period is 0.3s.

(b). The time period is 0.6s.

Explanation:

Faraday's law says that for one loop of wire the emf $\varepsilon$ is

$(1). \: \: \varepsilon = \dfrac{\Delta \Phi_B}{\Delta t }$

and since from Ohm's law

$\varepsilon = IR$ ,

then equation (1) becomes

$(2). \: \:IR= \dfrac{\Delta \Phi_B}{\Delta t }.$

(a).

We are told that the change in magnetic flux is $\Phi_B = 30Tm^2$ , the current induced is $I = 40A$ , and the resistance of the wire is $R = 2.5\Omega$ ; therefore, equation (2) gives

$(40A)(2.5\Omega)= \dfrac{30Tm^2}{\Delta t },$

which we solve for $\Delta t$ to get:

$\Delta t = \dfrac{30Tm^2}{(40A)(2.5\Omega)},$

$\boxed{\Delta t = 0.3s}$ ,

which is the period of time over which the magnetic flux increased.

(b).

Now, if the current had been $I =20A$ , then equation (2) would give

$(20A)(2.5\Omega)= \dfrac{30Tm^2}{\Delta t },$

$\Delta t = \dfrac{30Tm^2}{(20A)(2.5\Omega)},$

$\boxed{\Delta t = 0.6 s\\}$

which is a longer time interval than what we got in part a, which is understandable because in part a the rate of change of flux $\dfrac{\Delta \Phi_B}{\Delta t}$ is greater than in part b, and therefore , the current in (a) is greater than in (b).

7 0

3 years ago