An earth's satellite near the surface of the earth takes about 90 min per revolution. A satellite orbiting the moon also takes about $$90 \mathrm{~min}$$ per revolution. Then which of the following is true?
[where $$\rho_{\mathrm{m}}$$ is density of the moon and $$\rho_{\mathrm{e}}$$ is density of the earth.]
A bar magnet falls from rest under gravity through the centre of a horizontal ring of conducting wire as shown in figure. Which of the following graph best represents the speed (v) vs. time (t) graph of the bar magnet?
A uniform magnetic field B exists in a region. An electron of charge q and mass m moving with velocity v enters the region in a direction perpendicular to the magnetic field. Considering Bohr angular momentum quantization, which of the following statements is/are true?
A train is moving along the tracks at a constant speed u. A girl on the train throws a ball of mass m straight ahead along the direction of motion of the train with speed $$\mathrm{v}$$ with respect to herself. Then