Barron's 2nd Edition DT Q27

Barron's Book

27) This question asks us to find the correct force diagram of the figure represented above.

Gravity: Fundamentally, there is gravity acting directly downward.

Normal: Because the object is touching a surface, and because the object isn't accelerating, we can tell that there must be a normal force. It is important to remember that normal for is always perpendicular to the surface.

Friction: Finally, since the gravity isn't causing the mass to accelerate down the incline, there must some sort of resisting force - probably friction - acting parallel and up the ramp.

Now that we know all the forces acting on the mass, we can draw out what this would look like.

Answer: A