Question

Another question.

Answer 1

A rope is 50 meters long and (the rope) has the mass of 15kg. It hangs from one end off the tall building (the building is more than 50 meters). How much work is required to pull the rope up to the top of the building? (Use \(9.80~m/s^2\) for acceleration due to gravity.)

Answer 2

what steps do I have to perform ?

Answer 3

ALRIGHTIE A PHYSICS PROBLEM :)

Answer 4

F = ma

Answer 5

F= 9.8 m/s^2 times 15kg ?

Answer 6

The force of a body in motion is equal to its mass times its acceleration. In terms of this specific problem, Force is equal to a body's mass times its tangential acceleration (gravitation acceleration)

Answer 7

So lets see... F = (9.8 m/s^2)*(15kg) = 147 Newtons.

Answer 8

how do you know 147 Newtons ?

Answer 9

Work is W= F*d

Answer 10

So you need to find force to calculate work.

Answer 11

yes, 147, my bad.. you multiplied, I thought it would be a decimal, but it is not

Answer 12

If you want to be technical, it could be .147kN. :P

Answer 13

Anywho.

Answer 14

k, What do I do after I found the force ?

Answer 15

Since the Force is negative in this case (we are pulling it up) it is -147Newtons.

Answer 16

W = -147 Newtons * 50Meters.

Answer 17

pulling up is negative force ?

Answer 18

Yes, because we are pulling against gravity.

Answer 19

Also, wouldn't the rope be changing every bit you pull it, which would give like integral\[\int\limits_{0}^{50}...\]??

Answer 20

I mean changing in weight