Aphysicist attempts to push the crate up the incline. the physicist senses that if he applies slightly more force the crate will move up the incline but cannot muster enough strength to get the motion started. what can you say now about the force of friction acting on the crate? a. the frictional force points up the incline
b. the frictional force points down the incline
c. the frictional force is zero

B The frictional force points down the incline

Explanation:

Whenever a force is applied to an object, there is always a force of friction to oppose it. Sometimes, friction can be so close to zero that it is negligible (a simple case of friction being negligible is if something slides over an ice rink. The ice has a very low coefficient of friction).

In the case where a scientist is attempting to push a crate up an inclined plane, the force of friction opposes the movement. So the force of friction will act against the upwards movement, and move down the incline.

gets less

c)as speed changes, wavelength and frequency change.

everything changes!