Physics Questions and Answers

If the bob is fully immersed in the water, then the volume of water displaced will be equal to the volume of the bob = 4/3πr³, where r is the radius of the bob.
This volume of water in the cylinder = πr²l, where r = radius of the cylinder, and l = level of water rose in the cylinder.

Therefore, π x r² x l = 4/3 x π x 3³

Then r² = 36
r = √36
r = 6cm

At the height of 10m, its total energy is potential, given by P.E. = mgh = 1 x 10 x 10 = 100J.
But as the stone descends, its potential energy decreases, while its kinetic energy increases.
Half way during the fall, (h = 5m), its P.E. = 50J, and consequently, its K.E. should be 50J, such that from the principle of conservation of energy, the total energy of the stone at any instant should be conserved.

(p - 760)/(0 - 760) = (h - 0)/(80 - 0)
∴ (p - 760)/-760 = (20 - 0)/80
80(p-760) = -760(20-0)
∴80p - 60800 = -15200
80p = 60800 - 15200
80p = 45600
∴ p = 45600/80
p = 570mmHg

For a photoemitted electron,
eV = K.E._max, where V = stopping potential and K.E. = maximum kinetic energy of the photo emitted electron given by K.E. = Energy of incident rad - Work - function
= 5ev - 3ev = 2ev
∴ eV = 2eV
V = 2eV/e = 2V
∴ Stopping Potential = 2.0V

The force on the conductor is maximum when the conductor lies perpendicular to the field during which the maximum force is given as;
F = ILB = 0.8 x 2 x 0.5 = 0.8N