Physics Test 21...

Which of the following pairs of physical quantities does not have same dimensional formula ?

A plank is held at an angle α to the horizontal on two fixed supports A and B. The plank can slide against the supports (without friction) because of its weight Mg. Acceleration and direction in which a man of mass mm should move so that the plank does not move is:

A force  is acting at a point  The value of α for which angular momentum about origin is conserved is:

A simple pendulum of length ll is suspended from the ceiling of a cart which is sliding without friction on an inclined plane of inclination θ. What will be the time period of the pendulum?

The frequency of a sonometer wire is f but when the weights producing tension are completely immersed in water the frequency becomes f/2 and on immersing the weights in certain liquid the frequency becomes f/3. The specific gravity of the liquid is

A heat engine has an efficiency η. Temperatures of source and sink are each decreased by 100 K. Then, the efficiency of the engine.

Which of these is correct in regard to a magnet?

The mean lives of radioactive substances are 1620 y and 405 y for α- emission and β- emission respectively. Find out the time during which three-fourth of a sample will decay if it is decaying both by α- emission and β- emission simultaneously.

When the velocity of an electron increases, its de-Broglie wavelength

A charge q is located at the centre of a cube. The electric flux through any face is