Units and Measurements — Physics STD 11 Science — Question

When hot air rises up in the atmosphere why does its temperature at the top of the mountain become less than that at sea level?

In an open organ pipe, third harmonic is 450Hz. What is the frequency of fifth harmonic?

Does the moment of inertia of a rigid body change with the speed of rotation?

If the velocity of an object is constant, can its speed change? Why?

Which object will cool faster when kept in open air, the one at 300°C or the one of 100°C? Why?

In a fly wheel, most of the mass is concentrated at the rim. Explain why?

How earth retains most of the atmosphere?

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.

Angle of friction which the resultant of limiting friction and normal reaction makes with the normal, is numerically equal to ______.

If an object is rotating then is there definitely any torque acting on it?