# Tension Force

Topics: Pressure, Water, Density Pages: 2 (442 words) Published: June 4, 2012
What is the tension in the string in the figure?

T = W - FB    where T is the weightof the Al and FB  buoyant force due to thealcohol T = ρAl V g - ρE V g =(ρAl  - ρE) V g =(ρAl  - ρE) * 10E-4 *9.8     converting the volume to m3

Using 2700 for the density of Al and 790 for the density ofethyl alcohol

T = 1910 * 10E-4 * 9.8 = 1.87 N

A wood block with a density of 700 floats in water.
What is the distance from the top of the block to the water if the water is fresh? (a) density of fresh water is ρ_water = 1000 kg/m³ ΣF = 0
- (ρ_wood)g(V_wood) + (ρ_water)g(v_wood) = 0 (v_wood)/(V_wood) = (ρ_wood)/(ρ_water) (10 * 10 * h)/(10 * 10 * 10) = (700)/(1000) h = 7 cm the distance from the top of the block to the water is 10 - 7 = 3 cm (b) density of seawater is ρ_sea = 1030 kg/m³

(v_wood)/(V_wood) = (ρ_wood)/(ρ_sea)
(10 * 10 * h')/(10 * 10 * 10) = (700)/(1030)
h' = 6.79611 cm the distance from the top of the block to the water is 10 - 6.79611 = 3.20389 cm

The container shown in the figure is filled with oil. It is open to the atmosphere on the left. By the known formula,
presure = P  =  h dg
h is the level of height of the water column
d is the density of the oil
g is the acceleration due to gravity
(a) presure at A :  P_A =  h d g = (0.5m -0m ) (900 kg/m^3)(9.8m/s^2)= 4410  Pa   (b) presure between    B   and A  = P_B  - P_A  = hdg = (0.5 m - 0 m )(900)(9.8)= 4410 Pa

(c) presure betwewn   C   and A  = P_C - P_A  = hdg  = (0.5 m - 0 m )(900)(9.8)= 4410 Pa

What is the gas pressure inside the box shown in the figure? Height difference between gas and mercury h = 16 cm –6 cm = 10 cm = 0.1 m P = Po + Dgh Where  Po= atmospheric pressure = 1 atm = 101.3 * 10 ^ 3Pa  D = mercury = 13600 kg / m^ 3Plug the values weget P = ( 101.3 * 10^ 3 Pa) + (13328 Pa)   = 114628 Pa     (101325 Pa - 13328 Pa)=8.8*10^4 A 1.2-m-diameter vat of liquid is 2.4  deep. The pressure at the bottom of the vat is1.2 . What is the...