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3 years ago

A book rests on a table, exerting a downward force on the table. the reaction to this force is:

Physics

1 answer:

lapo4ka [179]3 years ago

4 0

The upward force the table exerts on the ground!
Equal and opposite forces.

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A 525 kg satellite is in a circular orbit at an altitude of 575 km above the Earth's surface. Because of air friction, the satel

Dafna1 [17]

Answer:

$1.69\cdot 10^{10}J$

Explanation:

The total energy of the satellite when it is still in orbit is given by the formula

$E=-G\frac{mM}{2r}$

where

G is the gravitational constant

m = 525 kg is the mass of the satellite

$M=5.98\cdot 10^{24}kg$ is the Earth's mass

r is the distance of the satellite from the Earth's center, so it is the sum of the Earth's radius and the altitude of the satellite:

$r=R+h=6370 km +575 km=6945 km=6.95\cdot 10^6 m$

So the initial total energy is

$E_i=-(6.67\cdot 10^{-11})\frac{(525 kg)(5.98\cdot 10^{24} kg)}{2(6.95\cdot 10^6 m)}=-1.51\cdot 10^{10}J$

When the satellite hits the ground, it is now on Earth's surface, so

$r=R=6370 km=6.37\cdot 10^6 m$

so its gravitational potential energy is

$U = -G\frac{mM}{r}=-(6.67\cdot 10^{-11})\frac{(525 kg)(5.98\cdot 10^{24}kg)}{6.37\cdot 10^6 m}=-3.29\cdot 10^{10} J$

And since it hits the ground with speed

$v=1.90 km/s = 1900 m/s$

it also has kinetic energy:

$K=\frac{1}{2}mv^2=\frac{1}{2}(525 kg)(1900 m/s)^2=9.48\cdot 10^8 J$

So the total energy when the satellite hits the ground is

$E_f = U+K=-3.29\cdot 10^{10}J+9.48\cdot 10^8 J=-3.20\cdot 10^{10} J$

So the energy transformed into internal energy due to air friction is the difference between the total initial energy and the total final energy of the satellite:

$\Delta E=E_i-E_f=-1.51\cdot 10^{10} J-(-3.20\cdot 10^{10} J)=1.69\cdot 10^{10}J$

8 0

3 years ago

Why is it very difficult for astronomers to find objects like planets and asteroids?

mezya [45]

It is difficult for astronomers to find object like planets and asteroids because it takes a lot of time to verify the objects locations and what surrounds a certain object in order to prove and be precise of its location

3 0

3 years ago

What could easily be converted into heat, light, or motion? A) Steel B) Iron C) Electricity D) Energy

julia-pushkina [17]

The answer is C.energy because it can make light and heat

5 0

3 years ago

The air pressure at the ocean surface a few miles from the shoreis most likely

frez [133]

The air pressure is most likely lower.

8 0

3 years ago

What is the mass of an object that creates 33,750 joules of energy by traveling at 30 m/sec?

nikklg [1K]

The Energy is Kinetic Energy.

Kinetic Energy = 1/2*mv², Where m is mass in kg, v is velocity in m/s

Energy is 33750 Juoles, v = 30m/s

1/2*mv² = E

1/2*m*30² = 33750

m = (2*33750) / (30²) Using a calculator

m = 75 kg

Mass of object is 75 kg.

5 0

3 years ago

Read 2 more answers