A student runs up a flight of stairs which info is not needed to calculate the rate of the student is doing work against gravity A the height of the flight of stairs B the length of flight of stairs C the time taken to run up the stairs D the weight of the student

B.

Explanation:

Given that a student runs up a flight of stairs which info is not needed to calculate the rate of the student is doing work against gravity A the height of the flight of stairs B the length of flight of stairs C the time taken to run up the stairs D the weight of the student

The rate of doing work is known as power.

Power = work done/time

Work done = energy = mgh

Since energy = mgh

Where mg = weight

And h = height

Time = time taken to run up the stairs.

Time, weight mg and height h will be needed while the Length of the flight is therefore not needed.

The correct answer is B.

fgravity=10x10=100n case 1

fgravity=30x20=600n case 2

6 times more

another example of kinetic energy would be,

kinetic energy   >     moving energy

answer   >   letter choice (c),   a hammer falling off a table.

hope that !                                         : )