Please answer the following questions about uniform circular motion.? Part (a) A planet orbits a star in a circular orbit at a constant orbital speed, which of the following statements is true?
All of these are correct.
The magnitude of the orbital velocity of the planet is unchanged, thus there is no acceleration and therefore no force action on the planet.
None of these are correct.
The planet experiences a centripetal force pulling towards its star.
The planet experiences no centripetal force.
The planet experiences a centripetal force pushing it away from its star.
Part (b) When a planet is orbiting a star, which force plays the role of the centripetal force?
The force resulting from the planets’ velocity around the star.
The force resulting from the centripetal acceleration.
The gravitational force
Part (c) Which of the following are true statements about uniform circular motion?
An object in uniform circular motion experiences a tangential force.
An object in uniform circular motion experiences a centripetal force, an equal and opposite centrifugal force, and a tangential force.
An object in uniform circular motion experiences a centripetal force and a tangential force.
An object in uniform circular motion experiences a centripetal force.
None of these choices are true.
An object in uniform circular motion experiences no forces.

a) The planet experiences a centripetal force towards its star

b) The universal attractive force (Gravitational force)

c)None of these choices are true.

Explanation:

This problem raise several claims, let's review some aspects of circular motion

            F = m a

the centripetal acceleration is

            a = v² / r

where v is the speed (modulus of velocity) that is constant and r is the radius

The direction of the acceleration is perpendicular to the motion.

Let's review the different claims

Part a) the orbital velocity is constant

The correct statement is: The planet experiences a centripetal force towards its star

Part b) what is the centripetal force

The correct statement: The universal attractive force (Gravitational force)

Part c) which statement is true

1) False. There can be no tangential force

2) False. There is a centripetal force that creates the movement, but there is no centrifugal force because the system is accelerated and there is no tangential force because the movement is circular.

3) False. There is no tangential force

4) True none is true

5) False. There is a force because movement has acceleration

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explanation: