Two neutral bodies of masses $m_1$ and $m_2$ are kept at a distance of $r \mathrm{~cm}$ from one another in a vacuum medium. A gravitational force Fracts between the two bodies. The entire set-up is then transferred, as it is, to a water medium. The force between the bodies is then $\mathrm{F}_{\mathrm{w}}$. The ratio of $F_v$ to $F_w$ is:
$4:3$
$1: 1$
$ 1:1.33$
$3: 2$
An electric coil is rated $400 \mathrm{~W}, 200 \mathrm{~V}$. It is cut into two equal parts and connected in parallel to the same source of 200 V . Calculate the percentage increase in energy produced per second.
$400 \%$
$ 100 \%$
$200 \%$
$300 \%$
Resonance is produced between a turning fork and a resonance column tube with upper end open and lower end closed by water surface. If the frequency of the tuning fork is 800 Hz , and first two resonances are observed at lengths $9.75 \mathrm{~cm}, 31.25 \mathrm{~cm}$,
Find the length at which the third resonance occurs? Also find the speed of sound.
52.75 cm and $344 \mathrm{~ms}^{-1}$
31.25 and $330 \mathrm{~ms}^{-1}$
62.60 cm and $335 \mathrm{~ms}^{-1}$
43.10 cm and $340 \mathrm{~ms}^{-1}$
A boy, standing at a certain height, kicks a football horizontally with a velocity of $19.6 \mathrm{~ms}^{-1}$. What will be the ratio of horizontal and vertical components of velocities after $2 s$ ?
$1: \sqrt{2}$
$\left(\frac{\sqrt{3}}{2}\right): 1$
$1: 1$
$ 1:0.5$
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