6. The first vertebrates appeared during
a. Precambrian time
b. the Paleozoic Era
C. the Mesozoic Era
d. The Cenozoic Era

Those organic structures that do not seem to play any important biological function in the organism that possesses them are known as vestigial structures.

A vestigial structure is one that has atrophied or lost its original function throughout the course of evolution.

Therefore, we can conclude that vestigial structures are structures that some organisms still conserve as an inheritance from their ancestors but that, for some reason or another, are no longer useful for the functioning of the same.

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A force of 50 N was applied to an object with a mass of 5 kg, then the acceleration of the object will be 10 m/s².

The rate of change in an object's velocity with respect to time is known as acceleration in mechanics. The vector quantity of accelerations. The direction of the net force that is acting on an object determines its acceleration.

Since acceleration has both a magnitude and a direction, it is a vector quantity. Velocity is a vector quantity as well. The definition of acceleration is the change in velocity vector over a time interval divided by the time interval.

There are several types of acceleration :

According to the question, the given values are :

Force, F = 50 N

Mass, m = 5 kg

Force = m × a

a = 50 / 5

a = 10 m/s².

Hence, the acceleration of the object will be 10 m/s².

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Option B is correct.Increasing the distance between the particles by a factor of 3 decrease the force between two charged particles by a factor of 9.

The electric force between the two charges is directly proportional to the product of the charge and inversely proportional to the square of the distance between them.

The electric force is found as;

[tex]\rm F = \frac{K q_1q_2}{r^2}[/tex]

The electric force between the two charges is directly proportional to the product of the charge.

The electric force is inversely proportional to the square of the distance between them.

Increasing the distance between the particles by a factor of 3 decreases the force between two charged particles by a factor of 9

Hence, option B is correct.

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Answer:

Explanation:

The father of the Multitude was Abraham. And he did precede the 10 commandments. But the story really has nothing to do with the 10 commandments.

He obeyed God's Command because it was God who issued it. Abraham had complete faith in God's ability to make things come out right. The sacrifice of Isaac was a test of faith.

I would advise you to answer true, but whoever wrote the question employed a twisted kind of logic. The sacrifice of Isaac had nothing to do with the 10 commandments. Thou Shalt not murder is not really covered by this circumstance.

So true might not be the correct answer. The question is very complex and does not lend itself to a simple True/ False answer.

Answer:

i cant see

Explanation:

but im smart

Answer:

Explanation:

Average velocity in the 24 m interval is 24 / 4 = 6 m/s

Average velocity in the 64 m interval is 64 / 4 = 16 m/s

There is a 4 second interval between the two points where average velocity equals actual velocity

a = Δv/t = (vf - vi) / t = (16 - 6) / 4 = 2.5 m/s²

s = v₀t + ½at²

24 = v₀(4) + ½(2.5)4²

4v₀ = 24 - 20

v₀ = 1 m/s

Not asked for but the velocity at the end of the first segment and beginning of the second segment is 11 m/s and final velocity is 21 m/s

The region a represents the distance of the electron from the nucleus.

According to the wave mechanical model of the atom, the probability of finding an electron within a given volume element (representing the atom) is the square of the wave function psi.

Since a is the region in space where there is the greatest probability of finding the electron in the atom, it follows that distance of the electron form the atom is always a.

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Answer:

d.

Explanation:

Radiometric dating is a method of dating geological/ archaeological specimens by determining the relative proportions of particular radioactive isotopes present in a sample. Carbon dating is a form of radiometric dating, but, in choice b, you're not comparing the carbon to the rock. One would compare ¹⁴C levels within the organic compound, just as one would compare radioactive isotope levels in a rock.

Answer:

Explanation:

a = F/m = 7500/2000 = 3.75 m/s²

v² = u² + 2as

s = (v² - u²) / 2a

s = (0² - 45²) / (2(-3.75))

s = 270 m

Answer:

Explanation:

Impulse results in a change of momentum

FΔt = mΔV

F = mΔV/Δt

The impulse acting on the hammer will equal the impulse acting on the nail

If we assume upward is the positive direction

F = m(vf - vi)/t

F = 1.2(1.0 - (-1.5)) / 0.001

F = 3000 N

A 1.2 kg hammer slams down on a nail at 5.0 m/s and bounces off at 1.0 m/s, if the impact lasts 1.0 ms, so the average force exerted on the nail is 3000 N.

According to Newton's third law, there is an equal and opposite force for every force. The hammer's force on the nail will be identical in size to the nail's force on the hammer, but opposite in direction.

Momentum shifts as a result of impulse.

FΔt = mΔV

F = mΔV/Δt

The force exerted on the hammer will be equivalent to the force exerted on the nail.

m(vf - vi)/t = F

F = 1.2(1.0 - (-1.5)) / 0.001

F = 3000 N

Therefore, F = 3000 N, if A 1.2 kg hammer slams down on a nail at 5.0 m/s and bounces off at 1.0 m/s, if the impact lasts 1.0 ms.

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Answer:

Water speed Plays a key role In determining The shape of it

Answer:

Explanation:

F = kx = 65 N/m(0.94 m) = 61.1 = 61 N

Answer:

Explanation:

If we ignore wind resistance, the time needed for the hay to drop from vertical rest is

t = √(2h/g) = √(2(300)/9.81) = 7.82 s

d = vt = 80.0(7.82) = 626 m before passing over the cow.

Answer:

Explanation:

Potential energy gets converted to rotational kinetic energy

a)         ½Iω² = mgh

½(mL²/3)ω² = mgL/2

       (L/3)ω² = g

              ω = [tex]\sqrt{3g/L}[/tex]

       v(CG) = (L/2) [tex]\sqrt{3g/L}[/tex]

Not sure if you wanted angular speed or tangential speed of the CG so I gave both.

b) v = Rω =  L [tex]\sqrt{3g/L}[/tex]

Answer:

I hope you liked my answer. Thank You!

Answer:

0.47 J

Explanation:

Answer:

Explanation:

Itz Deepika Here to help ~ .

Note:- If you have more questions then let me know !!

Answer:

Whales face an increasing number of threats including: For hundreds of years people hunted whales for their oil to fuel lamps and candles, to lubricate machinery and to make margarine, lipsticks and other products. They also used baleen whales to make tennis racquets and corsets!

Explanation:

Hi there!

We can use the work-energy theorem to solve.

Recall:

[tex]\large\boxed{E_i = E_f}}[/tex]

Initial energy = final energy

The initial energy is purely potential (she starts from rest), and, if we assign the bottom of the slope as the 0 line, her energy at the bottom is purely kinetic.

PE = mgh

KE = 1/2mv²

We can begin by setting the two equal:

mgh = 1/2mv²

Cancel out the mass and rearrange to solve for velocity:

2gh = v²

v = √2gh

Plug in given values and use g ≈ 10 m/s²:

v = √2(10)(20) = 20 m/s

Answer:

Explanation:

Ignoring friction, the acceleration will double

F = ma

2F = m(2a)

Answer:

Work = force * displacement

= 50 N * 20 Meter

=1000 Newton meter = 1000 joule .

Explanation:

The initial velocity of the 3250 Kg mass is 2.1 m/s. The distance covered by the larger mass in 5s is 4.7 cm.

In this problem, we have to apply the law of conservation of linear momentum. Note that;

Momentum before collision = Momentum after collision

m1u1 + m2u2 = m1v1 + m2v2

(2150 × 10) + (3250u1) = (2150 + 3250)5.22

21500 + 3250u1 = 5400 × 5.22

3250u1  = 28188 - 21500

u1 = 28188 - 21500/3250

u1 = 2.1 m/s

2) Again from the principle of conservation of linear momentum;

(0.40 × 3.5) + (0.60 × 0) = (0.40  × 0.70) + (0.60 × v2)

1.4 = 0.28 + 0.60v2

1.4 - 0.28 =  0.60v2

v2 = 1.87 cm/s

Using;

s = 1/2 ( u + v)t

s = 1/2(0 + 1.87) × 5

s = 4.7 cm

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There are many ways you can get wooden steps to be less slippery even when they are wet. Some ways are:  

*You can put a carpet on the steps. The fibers in a carpet usually have some friction which will give you a grip as you climb up and/or down and prevent you from falling.  

*You can apply anti-slip coatings like a paint on the steps. If you add some sand to the paint to add traction and lessen the slippery nature. Alternatively, If the wood has been waxed, you may consider using a wax remover.  

*You can fix a hand railing so that you can hold on to it when you go up and down the steps.

Answer:

Explanation:

Let x be the leaf spring compression distance

F = kx

5.20 x 10⁵ = (5.45 x 10⁵)x + (3.80 x 10⁵)(x - 0.500)

5.20 x 10⁵ = (5.45 x 10⁵)x + (3.80 x 10⁵)(x) - 1.90 x 10⁵

7.10 x 10⁵ = (9.25 x 10⁵)x

x = 0.76756...

x = 0.768 m

W = ½(5.45 x 10⁵)0.768² +  ½(3.80 x 10⁵)(0.768 - 0.500)²

W = 174,148.648648...

W = 174 KJ

Explanation:

Downstream: you just sum the magnitude of the velocity vectors:

3km/h + 4km/h = 7km/h

Upstream: difference of the magnitudes of the velocity vectors, in absolute value:

|3km/h - 4km/h| = 1km/h

Answer:

Explanation:

conservation of momentum

m(u) + M(0) = (m + M)v

u = (m + M)v/m

u = (0.250 + 1.35)(11.9) / 0.250

u = 76.16

u = 76.2 m/s

That's a fairly massive, and slow, bullet.

Answer:

[tex]\frac{a_{d}}{a_{i}} = \frac{(1 -mu)}{mu}[/tex]

= (1 - μ)/μ

Explanation:

Always draw a diagram!

Up the incline:

[tex]Fr_{max}[/tex] = maximum friction

[tex]Fr_{max}[/tex] = μk

k = R = mg.cos(45) = mg.sin(45)

Resolution of forces parallel to the slope:

F (Fp in the diagram) = force of propulsion

g = gravity

[tex]F - Fr_{max} = ma_{i}[/tex]

[tex]F -[/tex] μ.mg.cos(45) [tex]= ma_{i}[/tex]

Down the decline:

Resolution of forces:

[tex]mg.sin(45) - Fr_{max} = ma_{d}[/tex]

[tex]mg.sin(45) -[/tex] μ.mg.cos(45) [tex]= ma_{d}[/tex]

Then, find the ratio:

[tex]\frac{ma_{d}}{ma_{i}} = \frac{mg.sin(45) - mu.mg.cos(45)}{-F + mu.mg.cos(45)} \\\\ \frac{a_{d}}{a_{i}} = \frac{k - k.mu}{-F + k.mu} \\\\ = \frac{k(1 -mu)}{-F + k.mu}[/tex]

Potentially, there is no need to consider F in this situation, in which case:

[tex]\frac{a_{d}}{a_{i}} = \frac{k(1 -mu)}{k.mu} \\\\ = \frac{(1 -mu)}{mu}[/tex]

= (1 - μ)/μ

If the speed of the magnet is doubled, the induced voltage is twice as great

Faraday's law of induction states that whenever relative motion exists between a coil and magnetic field, a voltage will induce in the circuit and this voltage is proportional to the rate of change of the flux. The expression for the motional emf is as follows:

ε=Blv

Here, ε is the motional emf, B is the magnetic field, l is the length of the conductor, and v is the velocity at which the magnetic field changes.

The induced voltage by the moving magnet is directly proportional to the speed of the magnet. Therefore, an increase in the speed of the magnet will increase the induced voltage.

If the speed of the magnet is doubled, the induced voltage is twice as great

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Answer:

the movement of snail on the ground is in random motion.

the strings of the guitar is in oscillatory motion.

the whirling of stone tied with a thread is in circular motion.

Answer:

A. 340 meters/second

I think this is the right answer.