Answer:
a.1017.9N
b.1029.7N
c.T=380.6N
d.11.8 N
Explanation:
(a) The absolute pressure at the level of the top of the block is
Po=atmospheric pressure
g=gravity
h1=height
rh0=density of water
P1=Po+rho*g*h1
1.013*10^5+1000(9.81)(0.05)
1.0179*10^5Pa
at the level of the bottom of the block we have
P2=Po+rho*g*h2
1.013*10^5+1000(9.81)(0.17)
1.0297* 10^5 Pa
the downward force exerted on the top by the water is
Ftop=P*A== × = 1.0179* 10^5* 0.100
= 1017.9 N
and the upward force the water exerts on the bottom of the block , which is the buoyant force
Fbot== × = 1.0297 10^5 * 0.100 m
= 1029.7 N
(b) The scale reading is the tension, T, in the cord supporting the block.
if the block is at equilibrium, then sum of vertical forces
EFy=T+Fbot-Ftop-mg=0
T=mg+Ftop-Fbot
T=40*9.81-(1029.7-1017.9)
T=380.6N
(c) Archimedes principle state that, the buoyant force on the block equals the weight of the displaced water. Thus,
Buoyant force=rho *g*h
= = 1000* 0.100^2 * 0.120 m *9.80 m s=11.8 N
from the answer a Ftop-Fbot
1029.7-1017.9=11.8N, the same as the buoyant force
