Magnitude of acceleration = (change in speed) / (time for the change) .
Change in speed = (ending speed) - (starting speed)
= zero - (43 m/s)
= -43 m/s .
Magnitude of acceleration = (-43 m/sec) / (0.28 sec)
= (-43 / 0.28) (m/sec) / sec
= 153.57... m/s²
= 1.5... x 10² m/s² .
Have you ever looked up the density of a substance ? You ought to try it. Go ahead. Pick a substance, then go online or open up an actual book and find its density. You will never see any particular volume mentioned along with the density . . . because it doesn't matter. The whole idea of density is that it describes the substance, no matter how much or how little you have of it. The density of a tiny drop of water under a microscope is the same as the density of a supertanker-ful of water.
The best answer is A) <span>keep moving at a constant velocity until some forces act on them
As the man you're probably tired of hearing about said:
"Every object persists in its state of rest or in uniform motion in a straight line unless a new force acts upon it"
This is Isaac Newton's 1st law of motion, or the law of inertia.
Put more simply, objects in motion tend to stay in motion, and tend the maintain the same velocity (direction and speed) and objects at rest tend to stay at rest. </span>
