I have a manual transmission car.

Preconcept: I thought the clutch worked with two disks, when there's more friction between them, the transmission disk makes the other disk move. The friction is higher when there's more pressure between the disks, but also if the transmission disk moves faster, it makes the other disk move faster.

Situation: I'm at a slope mantaining the car stopped with the gear 1, throttling a little bit, with the clutch pressed just at the right spot to mantain the car stopped without going backwards.

Question: If I release the clutch, the car goes forward up the slope. But if I press the throttle maintaining the clutch in the sweet spot (not moving it at all), the car does not move forward. Why is that?

PS: Sorry I couldn't even articulate a succint question.