NECO Past Questions and Answers - Page 227

1,131.

A short chain is usually attached to the rear side of petro tanker trailing behind it to ensure that the

A.

charges generated by friction in the tanker are conducted to the earth

B.

chain vibrates in resonance with the tanker’s engine

C.

heat generated by friction in the engine is conducted to the earth

D.

petrol tanker is balanced on the road

E.

tanker does not exceed a certain speed limit

Correct answer is A

No explanation has been provided for this answer.

1,132.

Calculate the critical angle for light traveling from water to air. (Refractive index of water = 1.33)

A.

36.9°

B.

41.3°

C.

48.8°

D.

49.2°

E.

51.4°

Correct answer is C

critical angle formula = \(sin^{-1}\) \(\frac{n_2}{n_1}\)

→ \(sin^{-1}\) \(\frac{1}{1.33}\) = \(sin^{-1}\) 0.7518

= 48.75º

1,134.

Which of the following motions will be produced by a pair of equal, opposite and non-collinear parallel forces acting on a body?

A.

Oscillatory

B.

Random

C.

Rotational

D.

Translational

E.

Vibratory

Correct answer is C

A couple consists of two equal and opposite forces acting at a separation, so that net force becomes zero. When a couple acts on a body it rotates the body but does not produce any translational motion. Hence, only rotational motion is produced.

1,135.

A narrow, uniform glass tube, closed at one end, constains air which is sealed by a thread of mercury. The tube is placed first horizontally and then vertically with the open end at the top. Which of the following statements is correct?

A.

The length of the entrapped air in the horizontal position is less than that in the vertical position

B.

The length of the entrapped air in the vertical position is less than that in the horizontal position

C.

The length of the mercury column becomes shorter in the horizontal position than in the vertical position

D.

The length of the mercury column becomes shorter in the vertical position than in the horizontal position

E.

The pressure of the entrapped air is atmospheric in both cases.

Correct answer is B

No explanation has been provided for this answer.