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Tanya [424]
3 years ago
7

How many continents do have in africa​

Physics
1 answer:
Neporo4naja [7]3 years ago
5 0

Answer:

There was 7 continents in africa

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Find the kinetic energy K of a satellite with mass m in a circular orbit with radius R. Express your answer in terms of m, M, G,
ratelena [41]

Answer:

K=\frac{GmM}{2R}

Explanation:

The kinetic energy is defined as:

K=\frac{mv^2}{2}(1)

Here, m is the object's mass and v its speed. In this case the speed of the satellite is the orbital speed, which is given by:

v_{orb}=\sqrt\frac{GM}{R}(2)

Here, G is the gravitational constant, M is the mass of the object that the satellite is orbiting and R is the radius of its circular orbit. Replacing (2) in (1):

K=\frac{mv_{orb}^2}{2}\\K=\frac{m(\sqrt\frac{GM}{R})^2}{2}\\K=\frac{GmM}{2R}

3 0
4 years ago
A mass is undergoing simple harmonic motion. When its displacement is 0, it is at its equilibrium position. At that moment, its
Nostrana [21]

Answer:

Its speed is maximum and its acceleration is zero

Explanation:

- Concerning the speed:

In a simple harmonic motion, the speed can be determined through the law of conservation of energy. In fact, we have that the total mechanical energy of the system, which is sum of elastic potential energy U and kinetic energy K, is constant:

E=U+K=\frac{1}{2}kx^2+\frac{1}{2}mv^2

where k is the spring constant, x is the displacement, m is the mass and v is the speed.

We see that when the displacement is 0, x = 0: this means that the elastic potential energy U is also 0, therefore the kinetic energy K is maximum, and so the speed v is also maximum.

- Concerning the acceleration:

According to Newton's second law, the acceleration of the system is proportional to the net force:

a=\frac{F}{m}

the net force is just the restoring force of the spring, given by Hooke's law:

F=-kx

So, the acceleration is

a=-\frac{kx}{m}

and we see that when the displacement is zero, x = 0, and so the acceleration is also zero.

4 0
4 years ago
Manuel is holding a 5kg box. How much force is the box exerting on him?In what direction
soldi70 [24.7K]
The force the box is exerting on Manuel is the weight of the box, downward:
W=mg=(5 kg)(9.81 m/s^2)=49.05 N
and this force is perfectly balanced by the constraint reaction applied by Manuel's hand, pushing upward.
3 0
4 years ago
Which energy transformation occurs in the core of a nuclear reactor?
romanna [79]
The correct answer among the choices given is option B. The energy transformation that occurs in the core of a nuclear reactor is from nuclear energy to thermal energy. In a power plant nuclear fission which involves nuclear energy to heat up water around it. This part is  the core of the process.
5 0
4 years ago
Unlike eukaryotes, prokaryotes do not have:
xxMikexx [17]
D. a membrane bound nucleus , lmk if im right
5 0
3 years ago
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