A crate rests on a loading ramp. The ramp's surface pushes on the crate, as every surface does. Which way does that push point: straight up like a table's, or square-on to the ramp's tilted face?
Watch the same push on three surfaces: flat, vertical, and tilted.
A mug rests on a flat table. The table's push on the mug points straight up, square-on to the tabletop.
A hand presses on a vertical wall. The wall's push on the hand points horizontally, square-on to the wall.
A crate rests on a tilted ramp. The ramp's push on the crate points away from the ramp's face, square-on to it, not straight up.
The pattern: the normal force always acts perpendicular to the contact surface. That is the name's whole job: 'normal' is the old math word for perpendicular.
A crate rests on a ramp. Which way does the normal force on the crate point?
Tilt the surface, and the normal force tilts with it. The normal force follows the surface, not the sky.
A framed photo leans against a vertical wall. Which way does the wall's normal force on the frame point?
So to find a normal force's direction, look at the surface alone: the push is square-on to its face, pointing away from it.
Lena carries a serving tray and tilts it slightly; the sandwich stays put. Does the tray's normal force on the sandwich tilt with the tray?
A phone rests on a wedge-shaped stand tilted back at 20°. Which way does the stand's normal force on the phone point?
The normal force acts perpendicular to the contact surface.
The stand's face is tilted back by 20°, so the push is square-on to that tilted face.
Away from the stand's face, perpendicular to it: tilted 20° from straight up.
A gym ball is pressed against a vertical mirror wall. Which way does the wall's normal force on the ball point?
The surface is vertical, and the normal force is perpendicular to it.
Horizontally, straight out from the mirror wall.
A toolbox rests on a ramp that makes 30° with the ground. The normal force on the toolbox points:
Which statement about the normal force holds for every surface?
Jax presses a sticky note onto a vertical locker door to make it stick. While he presses, the door's normal force on the note points: