If you lift a seven pound object 54 inches how many joules of energy did you use?

-42.68 J  

Explanation:

Work done = weight x displacement

weight = 7 pound

           = (7 x 4.45) N

           = 31.15 N

Displacement = 54 inches

1 inch = 0.0254 m

54 in = 1.37 m

Work done = 31.15 N x 1.37 m x cos 180°

                   = -42.68 J

Thus, the amount of energy used to lift 7 pound object to 54 inches, 42.68 J of energy is used.

the chart show the masses and velocities of two colliding objects that stick together after a collision.

according to the law of conservation of momentum, the momentum of the object after the collision is  

answer

1,500

kg • m/s.