Answer:
0.035 N
Step-by-step explanation:
Density = mass/volume
D = m/v
m = D× v ..................... Equation 1
Where D = density of the ping-pong, v = volume of the ping-pong, m = mass of the ping-pong
Note: The ping-pong is spherical in shape.
v = 4/3πr²
Where r = radius, π = pie
d = 1.99 cm, π = 3.14
v = 4/3(1.99/2)²(3.14)
v = 4.12 cm³
Also D = 0.121 g/cm³
Therefore,
m = 0.121(4.12)
m = 0.499 g
W = mg
Where W = weight of the ping-pong
W = (0.499/1000)×9.81
W = 0.005 N.
From Archimedes principle,
Upthrust = density of water × volume of water displaced × acceleration due to gravity.
U = D'vg/1000...................... Equation 2
Note: The volume of water displaced is equal to the volume of the ping-pong.
given: v = 4.12 cm³, g = 9.81 m/s², D' = 1 g/cm³
Substitute into equation 2
U = 1(4.12)(9.81)/1000
U = 0.04 N
The force required to hold the ball completely submerged under water = U-W
= 0.04-0.005 = 0.035 N