A barometer kept in a stationary elevator reads $76 cm$. If the elevator starts accelerating up the reading will be
A
Zero
BEqual to $76 cm$
CMore than $76 cm$
DLess than $76 cm$
Easy
Download our app for free and get started
DLess than $76 cm$
d (d) $h = \frac{P}{{\rho g}}$
$h \propto \frac{1}{g}$. If lift moves upward with some acceleration then effective g increases. So the value of h decreases i.e. reading will be less than $76 cm.$
Download our app
and get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
A liquid flows in a tube from left to right as shown in figure. ${A_1}$ and ${A_2}$ are the cross-sections of the portions of the tube as shown. Then the ratio of speeds ${v_1}/{v_2}$ will be
A tank with a small hole at the bottom has been filled with water and kerosene (specific gravity $0.8$). The height of water is $3\,m$ and that of kerosene $2\,m$. When the hole is opened the velocity of fluid coming out from it is nearly ........ $ms^{-1}$ .(take $g\, = 10\, m s^{-2}$ and density of water $= 10^3\, kg\, m^{-3}$)
The limbs of a $U$ -tube glass are lowered into vessels $A$ and $B, A$ containing water. Some air is pumped out through the top of the tube $C$. The liquids in the left hand limb $A$ and the right hand limb $B$ rise to heights of $10\, cm$ and $12\, cm$ respectively. The density of liquid $B$ is ........ $g/cm^3$
A copper ball of radius $'r'$ travels with a uniform speed $'v'$ in a viscous fluid. If the ball is changed with another ball of radius $'2r'$ , then new uniform speed will be
A wide bottom cylindrical massless plastic container of height $9 \,cm$ has $40$ identical coins inside it and is floating on water with $3 \,cm$ inside the water. If we start putting more of such coins on its lid, it is observed that after $N$ coins are put, its equilibrium changes from stable to unstable. Equilibrium in floating is stable if the geometric centre of the submerged portion is above the centre of the mass of the object). The value of $N$ is closed to
A cylindrical tank of height $0.4\,m$ is open at the top and has a diameter $0.16\,m$ . Water is filled in it up to a height of $0.16\,m$ . How long it will take to empty the tank through a hole of radius $5 \times 10^{-3}\,m$ in its bottom .......... $\sec$
A solid sphere of specific gravity $27$ has a concentric spherical cavity and it just sinks in water. The ratio of cavity radius to that of outer radius of sphere is
A metallic sphere weighing $3 \,kg$ in air is held by a string so as to be completely immersed in a liquid of relative density $0.8$. The relative density of metallic is $10$. The tension in the string is ........ $N$
A hemispherical portion of radius $R$ is removed from the bottom of a cylinder of radius $R$. The volume of the remaining cylinder is $V$ and mass $M$. It is suspended by a string in a liquid of density $\rho$, where it stays vertical. The upper surface of cylinder is at a depth $h$ below the liquid surface. The force on the bottom of the cylinder by the liquid is