Characteristics of Energy
Which of the following statements about energy are correct? Select all that apply.
A. Energy can be created or destroyed
B. Energy is the ability to do work.
C. Energy is a material substance.
D. Energy can change from one form to another.
E. An object can only have one form of energy at a time.

The rigid beam is supported by the three suspender bars. bars ab and ef are made of aluminum and bar cd is made of steel. if each bar has a cross-sectional area of 450 mm2, determine the maximum value of p if the allowable stress is (σallow)st = 200 mpa for the steel and ( σallow)al = 150 mpa for the aluminum. est = 200 gpa and eal = 70 gpa.

Mutt and jeff are running along a path each pushing a cart loaded with rocks. if mutt's wagon has a mass two times greater than jeff's and they want to stay together, arriving at their destination at the same time, what must happen? a) jeff should slow down so mutt can catch up. b) mutt must use half as much force to push his cart. c) mutt must use twice as much force to push his cart. d) mutt and jeff will use the same force, but mutt will take bigger steps.

Explain the comparisons between nature and packingtown that appears on pages 81 and 82 answer