Units and Measurements — Physics STD 11 Science — Question

If no external torque act on a body, will its angular velocity remain conserved?

On winter nights, we feel warmer when clouds cover the sky than when the sky is clear. Why?

The displacement-time graph of a particle is parallel to time-axis, what is the velocity of the particle?

A metal block of density 6000kg m^-3 and mass 1.2kg is suspended through a spring of spring constant 200N m^-1. The spring-block system is dipped in water kept in a vessel. The water has a mass of 260g and the block is at a height 40cm above the bottom of the vessel. If the support to the spring is broken, what will be the rise in the temperature of the water. Specific heat capacity of the block is 250Jkg^-1 K^-1 and that of water is 4200Jkg^-1 K^-1. Heat capacities of the vessel and the spring are negligible.

Two satellites of masses 3m and m orbit the earth in circular orbits of radii r and 3r respectively. What is the ratio of their orbital speeds?

The pairs of physical quantities that have the same dimensions are:

1. Reynolds number and coefficient of friction.
2. Latent heat and gravitational potential.
3. Curie and frequency of light wave.
4. Planck's constant and torque.

What do you understand by positive and negative time?

Which vector can be associated with a plane area? And what is its direction?

Do mass and weight have the same dimensions?

A ferry boat loaded with rocks has to pass under a bridge. The maximum height of the rocks is slightly more than the height of the bridge so that the boat just fails to pass under the bridge. Should some of the rocks be removed or some more rocks be added?