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Vera_Pavlovna [14]
3 years ago
12

Which of the following is true about a planet orbiting a star in uniform circular motion? A. The direction of the velocity vecto

r is always changing. B. The velocity of the planet is constant. C. The speed of the planet is always changing. D. The acceleration vector of the planet points directly away from the star.
Physics
2 answers:
Sunny_sXe [5.5K]3 years ago
6 0

Answer;

A.The direction of the velocity vector is always changing.

Explanation;

-A circular orbit of a planet around a star is an example of uniform circular motion (its speed remains constant).

--When a planet has just the right speed (for a given radius of orbit), then it will travel in circular motion with a constant speed. This is called uniform circular motion. Note that the velocity vector changes direction although the speed is constant. This means that there must be a net force on the planet.

Luda [366]3 years ago
4 0
<span>As it is uniform circular motion therefore speed is constant. Therefore we can rule out option B. Also in circular motion the direction of velocity vector changes therefore velocity can't be constant. Therefore option B is incorrect as well. Also centripetal acceleration is always towards the center so option D is wrong as well. That implies option A is correct.</span>
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Read 2 more answers
Determine the energy required to accelerate an electron between each of the following speeds. (a) 0.500c to 0.900c MeV (b) 0.900
Aleonysh [2.5K]

Answer:

The energy required to accelerate an electron is 0.582 Mev and 0.350 Mev.

Explanation:

We know that,

Mass of electron m_{e}=9.11\times10^{-31}\ kg

Rest mass energy for electron = 0.511 Mev

(a). The energy required to accelerate an electron from 0.500c to 0.900c Mev

Using formula of rest,

E=\dfrac{E_{0}}{\sqrt{1-\dfrac{v_{f}^2}{c^2}}}-\dfrac{E_{0}}{\sqrt{1-\dfrac{v_{i}^2}{c^2}}}

E=\dfrac{0.511}{\sqrt{1-\dfrac{(0.900c)^2}{c^2}}}-\dfrac{0.511}{\sqrt{1-\dfrac{(0.500c)^2}{c^2}}}

E=0.582\ Mev

(b). The energy required to accelerate an electron from 0.900c to 0.942c Mev

Using formula of rest,

E=\dfrac{E_{0}}{\sqrt{1-\dfrac{v_{f}^2}{c^2}}}-\dfrac{E_{0}}{\sqrt{1-\dfrac{v_{i}^2}{c^2}}}

E=\dfrac{0.511}{\sqrt{1-\dfrac{(0.942c)^2}{c^2}}}-\dfrac{0.511}{\sqrt{1-\dfrac{(0.900c)^2}{c^2}}}

E=0.350\ Mev

Hence, The energy required to accelerate an electron is 0.582 Mev and 0.350 Mev.

4 0
3 years ago
the imagine above shows to opposite forces acting on a rolling cart, what can we say is true about affect of the forces on the c
cluponka [151]

Answer:

Here is my answer...

Explanation:

The cart will connect with the opposite force, and then the cart will come to a shuddering stop before moving in the direction of the oposite force.

Hope I helped! :)

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