Please explain the action of forces here

[Asad Raza]

Homework Statement

Two forces are acting on a 4.87-kg object that moves with acceleration 5.47 m/s^2 in the positive y-direction. If one of the forces acts in the positive x-direction and has magnitude of 12 N, what is the magnitude of the other force in N?

Homework Equations

F=ma

The Attempt at a Solution

I couldn't figure this out. If the object accelerates in positive y direction, then the resultant force must be in the same direction. Now, if one force is acting in positive x direction, how can another force act in such a way that the object moves in positive y direction. This is only possible when the second force acts to the north west direction. No?

 

[Eclair_de_XII]

Yes, your $\vec F$ will have both an x-component and a y-component. There's also one other essential force that acts on the object in the y-direction. Try drawing a diagram of the vectors you will be adding. I don't believe you'll need the x-component for this calculation, but someone feel free to correct me if I am wrong.

 

[haruspex]

There's also one other essential force that acts on the object in the y-direction

No. We are told two forces act, and there is no basis for assuming any gravity is present, nor that y is vertical.

I don't believe you'll need the x-component for this calculation

It will be needed.

 

[haruspex]

This is only possible when the second force acts to the north west direction. No?

It implies the second force has both x and y components, but necessarily exactly NW.

 

[Asad Raza]

Does the positive y direction imply that it will have no x component--it goes straight up. If yes, how would we get to know the angle at which it acts?
Also, the force that acts in positive x direction only has one component or will it have an upward component too? If yes, what angle?

 

[haruspex]

Does the positive y direction imply that it will have no x component--it goes straight up. If yes, how would we get to know the angle at which it acts?
Also, the force that acts in positive x direction only has one component or will it have an upward component too? If yes, what angle?

The way I read the question, the first force has an x component only and the acceleration has a y component only.

 

[Asad Raza]

The way I read the question, the first force has an x component only and the acceleration has a y component only.

So the only force that remains is the second force that SHOULD have two components: one to cancel the x component of 12N and the other one to accelerate the mass in positive y direction. Correct?

 

[haruspex]

So the only force that remains is the second force that SHOULD have two components: one to cancel the x component of 12N and the other one to accelerate the mass in positive y direction. Correct?

Right.

 

[Asad Raza]

Right.

Thank you so much.