Answer:
D. When the box is placed in an elevator accelerating upward
Explanation:
Looking at the answer choices, we know that we want to find out how the normal force varies with the motion of the box. In all cases listed in the answer choices, there are two forces acting on the box: the normal force and the force of gravity. These two act in opposite directions: the normal force, N, in the upward direction and gravity, mg, in the downward direction. Taking the upward direction to be positive, we can express the net force on the box as N - mg.
From Newton's Second Law, this is also equal to ma, where a is the acceleration of the box (again with the upward direction being positive). For answer choices (A) and (B), the net acceleration of the box is zero, so N = mg. We can see how the acceleration of the elevator (and, hence, of the box) affects the normal force. The larger the acceleration (in the positive, i.e., upward, direction), the larger the normal force is to preserve the equality: N - mg = ma, N = ma+ mg. Answer choice (D), in which the elevator is accelerating upward, results in the greatest normal force, since in that case the magnitude of the normal force is greater than gravity by the amount ma.
The most interesting thing about this problem is that in order to use all of the given information, you need to ignore the laws of Physics, and never mind what the stone would really do if dropped from a real bridge in the real world.
Average velocity = (displacement) / (time for the displacement)
Displacement =
Straight path from the start point to the finish point = 45 meters down .
Time = 4.6 seconds
Average velocity = 45/4.6 = <em>9.783 meters/second down</em>
==================================
In the real world, a dropped stone would only take 3.03 seconds
to fall 45 meters.
Alternatively, a stone that fell for 4.6 seconds from rest would fall
103.7 meters, with an average velocity of 22.5 meters/second down.
But we accepted the given information, and did the best we could do
with it.
That taxi will traveled 1500s by carrying the passenger.
It's called covelant bonding
Yes it is consider biology
