Which statements describes friction? check all that apply. it results from microscopic bumps and ridges. it causes a change in motion. it occurs in the same direction as the push force. it is the opposite to the direction of the motion. it is parallel to the surfaces that rub together.

How many seconds does it take a pebble released from rest off a bridge to fall 29.4 m ? what is the pebble's speed when it has fallen 29.4 m ?

Why do electron microscopes have higher resolving power than light microscopes?

The motor m applies a time-varying force of f (200 t) n, where t is in seconds. box b with mass 200 kg starts from rest, and the coefficients of kinetic and static friction are 0.2 and us 0.3 the acceleration due to gravity is g 9.8 m/s2 b 300 a) find the time ' when the box starts to move. b) calculate the speed of the crate at 3 s c) calculate the power delivered by the motor at t 3 s