According to Huygens's principle, what is the explanation for boundary behaviors? A.
Each point on a wave front acts as a source of secondary waves.

B.
Each point on a wave front stops moving as it progresses.

C.
Each point on a wave front partly reflects and partly refracts the wave.

D.
Most of the points on the wave front stop progressing.

A12-kg bag of groceries is tossed onto a table at 4.0 m/s and slides to a stop in 2.2 s . modify the equation fδt=δ (mv) to find the force of friction.

Which is the best for showing percentages of different types of cars sold(gas hybrid , electric , other ) in the united states ?

Which explanation describes the forces involved for a person to walk down the sidewalk? a. the person's feet push backward on the sidewalk; the sidewalk pushes backward on the person. b. the person's feet push forward on the sidewalk; the sidewalk does not push on the person. c. the person's feet push backward on the sidewalk; the sidewalk pushes forward on the person. d. the person's feet push forward on the sidewalk; the sidewalk pushes forward on the person.