Flight of a plane without lift on its wings

[DavidOB18]

Homework Statement

I was practicing qs. at the end of the chapter and came across this. Example 5 shows a model aeroplane in circular motion at the end of a string. The centripetal force is the tension. Redo Example 5, assuming that there is no upward lift on the plane generated by its wings. Without such lift, the guideline slopes downward due to the weight of the plane. For purposes of significant figures, use 0.900 kg for the mass of the plane, 17.0 m for the length of the guideline, and 19.0 and 38.0 m/s for the speeds.

Relevant Equations

I tried resolving its weight into it's components downslope and I think the net force is t-mg.

I don't know where to start with this as I can't visualise a diagram for it. Any help would be appreciated.

 

[haruspex]

I can't visualise a diagram for it

Please make some attempt to do so and post what you come up with. The question provides a lot of guidance.

 

[DavidOB18]

Does the centripetal force become t-mg as it is the net force.

 

[DavidOB18]

 

[DavidOB18]

That should be mg sin theta sorry.

 

[haruspex]

Does the centripetal force become t-mg as it is the net force.

As vectors, yes. But if you mean as scalars you need to take direction into account.

That should be mg sin theta sorry.

You did not define theta. If it is the angle to the horizontal then, yes, sin.
So what two scalar force balance equations does that give you?

 

[DavidOB18]

So is the diagram just a slope and no circular motion.

 

[haruspex]

So is the diagram just a slope and no circular motion.

You do not need to represent the motion in the diagram. Just show the forces that act on the object.
You have a choice in that. You can use the plane's frame of reference and centrifugal force, with the net force being zero, or an inertial frame with the net force being the centripetal force.

 

[DavidOB18]

Thanks for your help.