Question

Pages 64 to 65 of your reading material trace an extended problem that involes lifting a bag of sugar up to a shelf at first it is lifted to one shelf then it is lifted again to a second higher shelf.based on the numbers that are obtained from the calculations, which of the following is a correct conclusion?
a) the job gets easier the higher you lift the object.
b) the weight changes as the object is lifted
c) it is less work to lift the object all the way to it's final destination in one step.
d) the amount of work is the same whether the bag is moved all at once or in two stages, provided the total height lifted is the same in either case.

Answer 1

Answer:

d) the amount of work is the same whether the bag is moved all at once or in two stages, provided the total height lifted is the same in either case.

Explanation:

While moving the bag to the shelf in one shot we can say that the total work done is given as

$W = mg(2H)$

here we know that

2H = total height raised by the bag

now when we raise the bag to first shelf and then move it to next shelf

then we will have

$W = W_1 + W_2[tex][tex]W = mgH + mgH$

$W = 2mgH$

so the correct answer will be

d) the amount of work is the same whether the bag is moved all at once or in two stages, provided the total height lifted is the same in either case.