a librarian does 8J of work to stack 5 identical books on top of each other. if each book has a thickness of 4 cm, wat is the mass of the book?
Answer: 2 kg
plz help and show steps
thx
2007-10-20 07:40:37 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Physics
W= mg(0.04+ 0.08+0.12+0.16) = m*9.8 *0.40= 8
so m= 2kg if you take g = 10m/s^2
2007-10-20 07:59:41 · answer #1 · answered by santmann2002 7 · 0⤊ 0⤋
first, book has thickness of 4cm
then 5 books has a thickness of 5*4cm=20cm convert from cm to m
since 100cm =1m
then 20cm=(20/100)m=0.2m
but workdone=force*distance
workdone=8J,distance=total thickness of the book=0.2m and force exerted by the book=mass of the book multiplied by acceleration due to gravity(which is approximately 10m/s)
assuming that the mass of the book=m
then we have
8=m*10*0.2
8=m*2
therefore m=8/2
m=4kg
therefore the mass of the book=4kg
2007-10-20 08:14:24 · answer #2 · answered by newton 2 · 0⤊ 0⤋