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3 years ago

How fossils influence and change our understanding of the history of Earth and it's species.

Physics

1 answer:

ira [324]3 years ago

4 0

Answer:

Fossils are the preserved remains or traces of animals, plants, and other organisms from the past. Fossils are important evidence for evolution because they show that life on earth was once different from life found on earth today.

Explanation:

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Bob is pulling a 30kg filing cabinet with a force of 200N , but the filing cabinet refuses to move. The coefficient of static fr

vredina [299]

Answer:

$2.0\cdot 10^2 N$

Explanation:

The cabinet does not move: this means that the net force acting on it is zero.

Along the horizontal direction, we have two forces:

- The push exerted by Bob, F = 200 N, forward

- The frictional force, $F_f$ , which acts in the opposite direction (backward)

Since the net force must be zero, we have:

$F-F_f = 0$

So solving the equation we can find the magnitude of the friction force:

$F_f = F = 200 N=2.0 \cdot 10^2 N$

7 0

4 years ago

The critical angle for a substance is measured at 53.7 degrees. light enters from air at 45.0 degrees. at what angle it will con

faust18 [17]

When light travels from a medium with greater refractive index $n_1$ to a medium with smaller refractive index $n_2$ , there exists an angle (called critical angle) above which the light is totally reflected, and the value of this angle is given by
$\theta_c = \arcsin ( \frac{n_2}{n_1} )$
In this problem, we know that the critical angle is $\theta_c = 53.7^{\circ}$ , so we can find the ratio between the refractive indices of the two mediums:
$\frac{n_2}{n_1} = \sin \theta_c = \sin 53.7^{\circ} =0.81$
and since the second medium is air (n=1.00), the refractive index of the first medium is
$n_1= \frac{n_2}{0.81}= \frac{1.00}{0.81}=1.23$

In the second part of the problem, we have light entering from air ( $n_i = 1.00$ ) at angle of incidence of $\theta_i = 45.0 ^{\circ}$ , into the second medium with $n_r = 1.23$ . By using Snell's law, we can find the angle of refraction of the light inside the medium:
$n_i \sin \theta_i = n_r \sin \theta_r$
$\sin \theta_r = \frac{n_i}{n_r} \sin \theta_i = \frac{1.00}{1.23} \sin 45^{\circ}=0.574$
$\theta_r = \arcsin(0.574)=35.1^{\circ}$

3 0

3 years ago

as an aid in understanding this problem. The drawing shows a positively charged particle entering a 0.61-T magnetic field. The p

miv72 [106K]

Answer:

E = 420.9 N/C

Explanation:

According to the given condition:

$Net\ Force = 2(Magnetic\ Force)\\Electric\ Force - Magnetic\ Force = 2(Magnetic\ Force)\\Electric\ Force = 3(Magnetic\ Force)\\qE = 3qvBSin\theta\\E = 3vBSin\theta$

where,

E = Magnitude of Electric Field = ?

v = speed of charge = 230 m/s

B = Magnitude of Magnetic Field = 0.61 T

θ = Angle between speed and magnetic field = 90°

Therefore,

$E = (3)(230\ m/s)(0.61\ T)Sin90^o$

3 0

3 years ago

Celina has a water sample that’s contaminated with salt and microorganisms. Which method should she use to purify the water?

TEA [102]

Answer:

Reverse Osmosis and UV Treatment

Explanation:

Reverse Osmosis, commonly known as RO, process is very effective in removing salt content from water. This process is known as desalination. IN RO, a partially permeable membrane is used to remove unwanted molecules, ions, and large particles. RO will take care of both desalination and purification of water.

Further UV treatment can be done to kill any remaining microorganisms as these microorganisms can not withstand UV radiation.

5 0

3 years ago

Read 2 more answers

Light from a sodium lamp 1l = 589 nm2 illuminates two narrow slits. the fringe spacing on a screen 150 cm behind the slits is 4.

BartSMP [9]

d = 0.221 mm is the spacing (in mm) between the two slits..

here,

wavelength = 589 nm

D = 150 cm = 1.5 m

y = 4 mm

then ,

y = mλD/d

for m = `1

0.004 = 589*10^-9 * 1.5/d

d = 2.21*10^-4 m

d = 0.221 mm

slit spacing is 0.221 mm

The sesmic characteristics of a train depend on the speed of the train, the distance between the wheels, and the hardness of the ground beneath the rails.

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In a typical hydrogen bond, as atoms move further up the energy ladder, The distance between the energy levels decreases. For Scientists Working at Such Small Scales, these “charging times” are likely candidates for the cause of the distance effect.

Learn more about spacing here:

brainly.com/question/15862947

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7 0

2 years ago