A sinker is a weight used by fishermen.
A fisherman uses a sinker in the shape of a sphere with radius 0.75 cm.
The sinker is made of lead, which has density 11.34 gm/cm3.
What is the mass of the sinker?
What is the mass of a sphere of water, with the same radius as the sinker? The water has density ρω = 1 gm/cm3.
The drag force on a sphere of radius r moving with velocity v in water, is
Fd = ±½ cd ρωπ r2v2
where the sign ± is chosen so the drag force is in the direction opposite to v, and cd = 0.47 is the drag coefficient. Assume v < 0. the drag force on the sinker is
Three forces act on the sinker: the drag force Fd, the force of gravity -mg and the buoyancy force +mwg. here g="980" cm/s2 is the acceleration due to gravity.
Find the differential equation for the velocity v.