Question

what does a sled experience if it is dragged across the ground?
static friction
cohesive friction
rolling friction
kinetic friction
question 16
which type of friction keeps a pile of rocks from falling apart?
cohesive friction
rolling friction
static friction
kinetic friction

Explanation:

When a sled is dragged across the ground, it is in motion relative to the ground, so it experiences kinetic friction which acts against its motion. For a pile of rocks to stay in place and not fall apart, the friction that resists any relative motion between the rocks (when they are at rest relative to each other) is static friction. Cohesive friction is not a standard friction - related term in basic physics for these scenarios, and rolling friction applies when an object rolls over a surface.

Answer:

For the first question: D. kinetic friction
For the second question: C. static friction