I am completely lost with these problems and would appreiciate help. 1. a 2-kg balloon is filled with 5-m3 helium tied to the ground by a cord. if the density of the helium in balloon is pHE=.2kg/m3 and density of air outisde the balloon is pAIR=1.3 kg/m3. Determine the tension of the cord? 2. A 5-kg book is resting on a horizontal tabletop. A force is then applied parallel to the top of the book. if the coefficient of static friction between the book and the tabletop is .6, determine how much the top of the book will shear before the book starts to slide along the tabletop. assume thickness of the book is 3cm, face of the book is 20 cm by 25 cm, and the shear modulus is S=4410 Pa.