I nd Hel Please? Which type of friction prevents a pile of rocks from falling apart?

rolling friction

static friction

cohesive friction

kinetic friction

Many machines- including inclined planes such as ramps- increase the strength of the force put into the machine but decrease the distance over which the force is applied.

Which type of wave can travel without a medium

Sound travels slower in colder air that it does in warmer air. make a claim about the effect of air temperature on the speed of sound. support your claim with evidence