Question

if the weight of stone in air is 70 N, weight of same stone in tap water 60 N and in salty water is 50 N, then find volume of the object?

Answer 1

Answer on Question#38860 – Physics – Other

If the weight of stone in air is 70 N, weight of same stone in tap water 60 N and in salty water is 50 N, then find volume of the object?

Solution:

P = 70N – weight of stone in air

$\rho_{\mathrm{t}} = 1000 \frac{\mathrm{kg}}{\mathrm{m}^{3}}$ – density of tap water;

$\mathrm{P_t} = 60\mathrm{N}$ – weight of stone in tap water

$\rho_{\mathrm{s}} = 1025 \frac{\mathrm{kg}}{\mathrm{m}^3}$ – density of salty water;

$\mathrm{P_s} = 50\mathrm{N}$ – weight of stone in salty water

Newton’s second law for a stone in the air:

$$P = m g = 70 N$$

Newton’s second law for a stone in the in tap water:

$$P _ {t} = m g - \rho_ {t} g V$$

(1) in (2):

$$V = \frac {P _ {t} - m g}{\rho_ {t} g} = \frac {P - P _ {t}}{\rho_ {t} g} = \frac {P - P _ {t}}{\rho_ {t} g} = \frac {7 0 N - 6 0 N}{9 . 8 \frac {N}{k g} \cdot 1 0 0 0 \frac {k g}{m ^ {3}}} = 1 0 2 0 \mathrm {c m} ^ {3}$$

Answer: volume of the object is equal to $1020~\mathrm{cm}^3$.