Circular motion/ speed increases at a constant rate

[YMMMA]

Homework Statement

If an object moves in a circular path with a speed that increases at a constant rate, which of the following can be concluded?

(A) The radial component of the force acting on the object is zero.
(B) The net force acting on the object is zero.
(C) The net force acting on the object is directed toward the center of the circle.
(D) The net force acting on the object has a radial component and a tangential component that are equal at all times
(E) The tangential component of the force acting on the object is constant.

Homework Equations

Centripetal force = mass times centripetal acceleration.

The Attempt at a Solution

I[/B] learned that speed is constant in circular motion, so does its centripetal force and acceleration. Velocity is tanget to the force and acceleration and that’s why it accelerates while maintaining its speed. But for this situation why and how the speed is increasing. I have no idea.

 

[BvU]

I learned that speed is constant in circular motion

You shouldn't have. Why 'invent' angular acceleration if what you learned is the case ?

Again, your relevant equations don't cut it. Think of something better.

 

[haruspex]

Velocity is tanget to the force and acceleration and that’s why it accelerates while maintaining its speed.

I assume you mean that if the speed is constant then velocity is normal to the force and to the acceleration, and that is why it can have a nonzero acceleration at constant speed.
Anyway, as BvU notes, you are told the speed is not constant here.

 

[YMMMA]

I think I will understand it if I looked for the topic of rotational dynamics. I will make sure I know them well before coming back to that question.

 

[YMMMA]

So yeah, I looked for this lesson, non-uniform circular motion, and got that because it speeds up it has a radial and tangential acceleration. Thus, It has a net acceleration, and for the force it also has a radial, tangential and a net force. That means I have to choose between E and D. I am confused actually. If it is increasing at a constant rate, that means thant the tangential acceleration is constant and also its tangential force. What about the radial one? Is it constant, too? But I would choose E.

 

[haruspex]

What about the radial one?

What equation do you know regarding radial (centripetal) acceleration?

 

[YMMMA]

It is velocity squared divided by the radius. But the velocity is increasing, so it should increase as well. Right?

 

[haruspex]

It is velocity squared divided by the radius. But the velocity is increasing, so it should increase as well. Right?

Right.