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3 years ago

Which law of motion accounts for the following statement?"The gravity of the Sun causes the planets to move in a circular path."

2 answers:

8 0

The law that accounts for that exact statement is the law that says that
most people don't understand these things very well.

A better statement is:
"The gravitational forces between the Sun and each planet cause each planet
to move in an elliptical path."

The laws that account for that behavior are:

-- Newton's second law of motion: (Force) = (mass) x (acceleration)

-- Newton's law of universal gravity

Finger [1]3 years ago

8 0

Explanation :

The gravity of the Sun causes the planets to move in a circular path. This is because of Newton's first law of motion.

According to Newton's first law, the body will remain at rest or in uniform motion untill external unbalanced force acts.

There are two forces acting on planets i.e. gravitational force and inertia of their orbits. So, form Newton's first law the planets keeps on moving in a circular path.

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You have a grindstone (a disk) that is 98.0 kg, has a 0.335-m radius, and is turning at 100 rpm, and you press a steel axe again

Alika [10]

Answer:

$a=0.276$

Explanation:

From the question we are told that:

Mass $m=98.kg$

Radius $r=0.335$

Angular velocity $\omega=100rpm$

Radial force of $F_r=23.6 N.$

Kinetic coefficient of friction $\mu=0.192$

Generally the equation for Kinetic Force is mathematically given by

$F_k=\mu.F_r$

$F_k=0.192*23.6$

$F_k=4.5312$

Generally the equation for Torque on Center is mathematically given by

$Ia=f_k*r$

Where

$I=\frac{Mr^2}{2}$

Therefore

$a=\frac{2f_k}{Mr}$

$a=\frac{2*4.5312}{98*0.335}$

$a=0.276$

Therefore Angular acceleration of the grindstone is

$a=0.276$

4 0

2 years ago

How many satellites exist in Earth’s orbit today?

stepan [7]

So we want to know how many satellites exist in Earth's orbit today. If by satellites we mean artificial vehicles made to orbit the Earth, then, according to Goddard Space Flight Center's list, there is 2271 satellite in the Earths orbit today. So the correct answer is 2271.

6 0

3 years ago

A car travels eastwards at 60km/h for 2h, then travels northwards at 20km/h for 8h. Find,

sveta [45]

Answer:

$a) Average\ Speed=28\ km/h\\b) Average\ Velocity= 20\ km/h$

Explanation:

$We\ are\ given\ that,\\Velocity\ of\ the\ car\ Eastwards=60\ km/h\\Time\ taken\ by\ the\ car\ Eastwards=2\ h\\Velocity\ of\ the\ car\ Northwards=20\ km/h\\Time\ taken\ by\ the\ car\ Northwards=8\ h\\Hence,\\As\ we\ know\ that,\\Speed=\frac{Distance}{Time}\\Distance= Speed* Time\\Now,\ lets\ find\ the\ distance\ covered\ by\ the\ car\ in\ both\ the\ cases.$

$Hence,\\Distance\ Covered\ During\ its\ Eastward\ Journey=60*2=120\ km\\Distance\ Covered\ During\ its\ Northward\ Journey=20*8=160\ km\\Now,\\As\ we\ know\ that\ Average\ Speed=\frac{Total\ Distance}{Total\ Time} \\Here,\\Total\ distance\ of\ the\ car=Distance\ Covered\ During\ its\ Northward\ Journey+Distance\ Covered\ During\ its\ Eastward\ Journey\\Hence,\\Total\ distance\ of\ the\ car=120+160=280\ km\\Total\ time\ taken\ by\ the\ car=8+2=10\ hours\\Hence,\\$ $Average\ Speed\ Of\ the\ Car\ throughout\ its\ journey=\frac{280}{10}=28\ km/h$

$Now,\\For\ Average\ Velocity\ we\ need\ to\ consider\ displacement\ as:\\Average\ Velocity\ =\frac{Total\ Displacement}{Total\ Time} \\Now,\\As\ we\ already\ know\ that\ displacement\ is\ the\ shortest\ distance\\ from\ the\ initial\ to\ the\ final\ point.\\We\ observe\ that, \\The\ car\ forms\ a\ right\ triangle\ during\ its\ complete\ journey.\\Hence,\\As\ we\ already\ know\ that,\\Distance\ travelled\ Eastwards= 120\ km\\Distance\ travelled\ Northwards= 160\ km\\Hence,\\$ $We\ may\ apply\ Pythagoras\ Property\ to\ find\ the\ net\ displacement.\\Hence,\\a^2+b^2=c^2\\120^2+160^2=c^2\\14400+25600=c^2\\40000=c^2\\c=\sqrt{40000}\\c=200\\Hence,\\Total\ displacement=200\ km\\Total\ Time\ taken=2+8=10\ hours\\Hence,\\Average\ Velocity\ Of\ the\ Car=\frac{200}{10}=20\ km/h$