Can anyone explain how friction can be in the direction of the net force as explained in EK physics Lecture 2.
Actiq said:Can anyone explain how friction can be in the direction of the net force as explained in EK physics Lecture 2.
shantster said:I haven't gotten to that point in the EK series, but I remember learning this in physics.
Say you have a pick up truck and a box is in the tailgate. (Let's just pretend this is a Caddilac truck with it's carpeted tailgate so we have lots of friction ) You accelerate in the forward direction and the box does not slide. The net force is in the direction that the truck is moving because the acceleration is in that direction. The friction between the box and the tailgate is also in that direction because otherwise the box would slide towards the back of the tailgate. If you think about it, the box would want to stay in the same place that it was before the truck began moving and so if there was no friction between the two, it would slide off the back of the tailgate. Thus, the friction is occurring opposite to the direction of motion that the box wants to go (backwards) and so it is in the same direction as the net force (forward).
Hope that helps!