Physics (CDS-Solved Paper)

Circular motion is a movement of an object along the circumference of a circle or rotation along a circular path. It can be uniform with constant angular rate of rotation and constant speed or non-uniform with a changing rate of rotation.

Since, the object’s velocity vector is constantly changing direction, the moving object is undergoing acceleration by a centripetal force in the direction of the centre of rotation without this acceleration, the object would move in a straight line, according to Newton’s laws of motion. Hence, the acceleration of the car is a non-zero but not a constant.

Given, speed of sound = 340 m/s

Let the distance of the mountain from the source of sound is d.  To heard echo after 5 s, sound will travel 2d distance. Since Echo is repection of sound which is reflected from any surface.

Given, power of electric bulb = 100W
Duration used each day = 10h
Number of days = 30
Total energy consumed by the electric
bulb = Power × Duration
= × 100 10 h/day × 30 days
= 30000 30 kWh
So, energy consume is 30 units.

Rutherford’s α-particle scattering experiment leads to the discovery of atomic nucleus. He proposed that, there is a positively charged spherical centre in an atom called nucleus.

The ratio of the observed size of specimen by a spherical mirror to the size of the actual, is called the linear magnification by the spherical mirror, it is denoted by m.
i.e.  m = I/O
where, I = observed size of specimen and O = actual size of the object.

The evaporation is a surface phenomenon. The rate of evaporation increases on increasing the surface area of the liquid.
A substance that has a larger surface area will evaporate faster, as there are more surface molecules that are able to escape.

If an object is at rest, then the time-distance graph is as below
Hence, graph is horizontal.

If the speed of a moving magnet inside a coil increases, the electric current in the coil increases. Whenever, a magnetic field and an electric conductor move relative to one another, so the conductor crosses lines of force in the magnetic field. Hence, the current produced by electromagnetic induction is greater.

An octave or perfect octave is the interval between one musical pitch and another with double its frequency. Hence, option (c) is correct.

Soap solution used for cleaning purpose. When soap is mixed in water, a colloidal solution is formed. The soap solution has soap micelles which are an aggregate of soap molecules. These micelles are large and they scatter light. That is why the soap solution appears cloudy.