Posted by **Dan** on Sunday, May 6, 2012 at 11:05pm.

A scuba diver searches for treasure at a depth of 20.0m below the surface of the sea. at what pressure must the scuba device deliver air to the diver? (density of sea water= 1030kg/m^3;atmospheric pressure= 1.013x10^5 pa)

another one

A king's crown is said to be solid gold but may be made of lead and covered with gold. when it is weighed in air, the scale reads 0.475 kg. when it is submerged in water the scale reads 0.437 kg.is it solid gold? if not, what percent is mass is gold? (density of gold= 19.3x10^3 kg/m^3)

- Physics. Need urgent help. -
**Elena**, Monday, May 7, 2012 at 4:32am
1.

p= ρ•g•h + p (atm)=1000•9.8•20 + 101325= =2.97•10^5 Pa.

2.

(a)

m=0.475 kg, m1 =0.437 kg

m1•g = m•g – F(buoyancy) =>

m1•g = m•g – ρ(w)•V•g,

V= (m - m1)/ρ(w) = (0.475-0.437)/1000 =3.8•10^-5 m^3.

m1•g = ρ(x) •V•g – ρ(w)•V•g ,

m•g = ρ(x) •V•g,

ρ(x) = m/V = 0.475/3.8•10^-5 =12.5•10^3 kg/m^3

(b)

19.3•10^3•x +11.4•10^3•(100-x) = 12.5•10^3•100,

19.3•x+11.4•(100-x) = 12.5•100,

7.9•x = 110,

x =13.92% ≈14%.

The crown is roughly 14% gold and 86% lead.

## Answer This Question

## Related Questions

- physics - A scuba diver searches for treasure at a depth of 20.0m below the ...
- Physics - the pressure at a point below a point below the surface of the sea is ...
- chemistry... confusing! - a scuba diver breathing normal air descend to 100 m of...
- physics - If a scuba diver descends too quickly into the sea, the internal ...
- physics - A scuba diver must decompress after a deep dive to allow excess ...
- chemistry - It decreases? If the air pressure increased, wouldn't that make the ...
- math - The pressure on a scuba diver at sea level is 14.7 pounds per sq inch (...
- algebra - The pressure on a scuba diver at sea level is 14.7 pound psi.The ...
- Physics - A scuba diver must decompress after a deep dive to allow excess ...
- math - underwater pressure can be found using the formula p=L+d/33 where p is ...

More Related Questions