You did 150 joules of work lifting a 120-newton backpack.

a. How high did you lift the backpack?

b. How much did the backpack weigh in pounds?

In the given question, we already know

Work done = 150 joules

Force = 120 Newton

Now we know from the study of physics that

Distance (D) = Work done / Force

(a) To find the height upto which the backpack has been lifted,

D = Work done / Force

= 150 / 120

= 15 / 12

= 5 / 4

= 1.25

So the backpack was lifted to a height of 1.25 metres.

(b) Now we have the find the weight of the backpack in pounds

We know that 1 pound = 4.448 Newton

So if

4.448 Newton = 1 pound

Then

120 Newton = (120 / 4.448) pounds

= 26.978 pounds

So the backpack weighed 26.98 pounds.