A 3000-lb wrecking ball hangs from a 10-ft cable of density 10 lb/ft attached to a crane. Calculate the work done if the crane lifts the ball from ground level to 10 ft in the air by drawing in the cable.

9514 1404 393

  30,500 ft·lb

Step-by-step explanation:

The 3000 lb ball is raised 10 ft, so (3000 lb)·(10 ft) = 30,000 ft·lb is the work done on it.

The weight of the cable is (10 ft)·(10 lb/ft) = 100 lb. Its center of mass is at its midpoint, 5 ft above the ground. When all of the cable is raised to a height of 10 ft above the ground, that center of mass is elevated 5 ft. The work done on the cable is ...

  (100 lb)·(5 ft) = 500 ft·lb

The total work done on the ball and cable is ...

  30,000 ft·lb +500 ft·lb = 30,500 ft·lb

question 1 is 8, question 2 is 9, question 3 is 24

step-by-step explanation:

now, the numbers they give you at the top are the key. from there, you just have to plug and chug! let's try 1, 2, and 3!

key: a=3, b=5, c=6

1. a+5

remember, a=3, so we plug that in to get 3+5=8

2. 15-c

c=6, so we plug that in to get 15-6=9

3. 4b

b=6, so we plug it in to get 4*6=24

time to try the rest on your own! if you put the answers below in a comment, i'll check them for you!

the first one is x^2+2x+2

the second one is x^2+4

the last one is x^2-4x+8