Test : Physics - 1 - NDA MCQ

Escape velocity is independent of mass of the object. It depends only on the mass of the planet as.

If the water vapor content stays the same and the temperature drops, the relative humidity increases. If the water vapor content stays the same and the temperature rises, the relative humidity decreases. This is because colder air doesn't require as much moisture to become saturated as warmer air.

The specific resistance (resistivity) of a metallic conductor nearly increases with increasing temperature as shown in figure. This is because, with the increase in temperature the ions of the conductors vibrate with greater amplitude and the collisions between electrons and ions become more frequent, over a small temperature range (up to 100°C). The resistivity of a metal can be represented approximately by the question

The factor a is called with temperature coefficient of resistivity. 
 

Therefore, acceleration is not constant but time dependent.

The first ionization energy generally increases ongoing across a period. This is because on crossing a period, more protons are being added to the nuclei of the atoms. This results in an increase in nuclear charge. The electrons in the outer energy levels will be more tightly held, and more difficult to remove.

Transition elements containing one or more unpaired electrons show paramagnetic behavior where the effects of individual electrons are not mutually compensated. The magnetic moment due to unpaired electron spins is aligned parallel to the external magnetic field more effectively.

As the external pressure increases the boiling point increases. Latent heat of vaporization means the energy required to overcome the intermolecular interactions for increasing the volume when a liquid boils, so latent heat of vaporization decreases as the boiling point increase

A vacuum is completely empty. Light traveling through a vacuum will encounter nothing of which is scattered so it can obtain its maximum speed.

When a ray of light enters a glass slab from the air, the velocity and wavelength decrease. V=nℷ , Where velocity and wavelength are directly proportional.

If the body is moving with uniform acceleration in the displacement-time graph, the body covering an unequal distance in equal interval of time and the speed is increasing and the slope is positive.

Work is only said to be done when there is displacement. The work done on a body moving in a circular path is also zero. This is because, when a body moves in a circular path, then the centripetal force acts along the radius of the circle, and it is at right angles to the motion of the body.

when light travels from one medium to another only speed of the light and wavelength changed and frequency does NOT change, it remains constant in all medium. The speed of light and wavelength changes in order to maintain the constant frequency.

In a circular motion, particle repeats its motion after equal intervals of time. So, a particle moving on a circular path is periodic but not simple harmonic as it does not execute to and fro motion about a fixed point.

Resistance of a semiconductor decreases with the increasing temperature. Pure silicon is a semiconductor.

Given, initial velocity (u) = 3i ̂+4j ̂

Final velocity (v) =? 

Acceleration (a) = (0.4i ̂+0.3j ̂)

Time (t) = 10 s 

From first equation of motion, v = u + at 

v = 3i ̂+4j ̂+10(0.4i ̂+0.3j ̂) 

v = 7i ̂+7j ̂⇒|v|=7√2

The potential energy of a system increases, if work is done by the system against a conservative force.

As we know that

Angular momentum L = m (r x v)

So, here angular momentum is directed along a line perpendicular to the plane of rotation.

The linear acceleration of Centre of mass will be a =F/m, wherever the force is applied. Hence, the acceleration will be same whatever the value of h may be.

The wettability of a surface by a liquid depends primarily on angle of contact between the surface and the liquid.