Hi.  Does anyone have the solutions worked out for the skill builders #46 and #49? Thank you!

Peggy - just checking - do you mean the #46 and #49 in the above Work and Energy Chapter problems? #46 is "A spring stores..." and #49 is "A 5 kg block...."  If so, here's how to do them.  If not - please let me know if I have the right problems.

#46:  Use EPE = 1/2 kx^2. Rearrange: k = 2 EPE/x^2 = 2(96 J)/(.05 m)^2 = 76,800 N/m

#49:  Use Delta GPE = GPE final - GPE initial = mgh - 0 =(5kg)(9.8 m/s^2)(28 m) = 1,372 J

John