How does the force of friction for a sliding object vary with the area of contact?

Which atomic model was proposed as a result of j. j. thomson’s work?

The uniform slender bar rests on a smooth horizon- tal surface when a force f is applied normal to the bar at point a. point a is observed to have an initial acceleration aa of 20 m/s2, and the bar has a corre- sponding angular acceleration of 18 rad /s2. deter- mine the distance b.

Which sound characteristic is not affected by the relative motion of an object