# Competitive Exams: Physics MCQs (Practice_Test 18 of 35)

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- If the linear density of a rod of length 3 m varies as l = 2 + x, then the position of the centre of gravity of the rod is
- m
- m
- m
- m

- The maximum velocity of a simple harmonic motion represented by y = 3 sin (100t + p/6) is given by
- 300
- 3p/6
- 100
- p/6

- A simple pendulum of length L is set up inside a wagon sliding down a smooth inclined plane of inclination with the horizontal. The period of oscillation recorded by an observer inside will be
- 2p (L/g cos q)
- 2p (L/g sin q)
- 2p (L/g)
- 2p (L cos q) =

- In an elastic one-dimensional collision between two particles, the relative velocity of approach before collision is
- greater than the relative velocity of separation after collision
- less than the relative velocity of separation after collision
- equal to the relative velocity of separation after collision
- less than the relative velocity of separation if the incoming particles heavier than the target particle.

- Annihilation of 1 gm of matter could theoretically yield electric energy of the order of
- 1032 eV
- 1013 eV
- 103 eV
- l eV

- The rest mass of the photon of frequency v is
- zero
- hv
- hv/c2
- infinite

- In the case of a fluid, Bernoulli՚s theorem expresses the application of the principle of conservation of
- linear momentum
- energy
- mass
- angular momentum

- Small droplets of 1iquid assume spherical shape because
- energy due to surface tension is lowest for a sphere
- energy due to surface tension is the highest for a sphere.
- volume energy is the highest for a sphere
- surface tension acts against the force of gravity