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JAMB Physics Past Questions & Answers - Page 66

326.

Palm oil from a bottle flows out more easily after it has been heated because the

A.

Molecules do not increase speed during the heating

B.

Viscosity of oil is reduced

C.

Oil molecules force each other out

D.

Adhesion between the oil molecules and those of the bottle is increased

Correct answer is B

If a liquid is heated the particles are given more energy and move faster and faster expanding the liquid.The result is that liquids show a reduction in viscosity with increasing temperature. With high temperatures, viscosity increases in gases and decreases in liquids, the drag force will do the same.

327.

Which of the following is the dimension of pressure

A.

ML1T2

B.

MLT2

C.

ML2T3

D.

ML3

Correct answer is A

Pressure = ForceArea

  Pressure = m × at

  = MLT2L×L

  = ML1T2

328.

To keep a vehicle moving at a constant speed V requires power P from the engine. The force provided by the engine is

A.

Pv

B.

(12)V

C.

PV

D.

PV2

Correct answer is A

P = F × S1
P = F x V
F = PV

329.

A particle of mass M initially at rest splits into two. If one of the particles of mass M1 moves with velocity V1 , the second particle moves with velocity

A.

M1V1MM1

B.

M1V1M1M

C.

M1V1M

D.

MVMM1

Correct answer is B

No explanation has been provided for this answer.

330.

The friction which exist between two layers of liquid in relative motion is called

A.

Capillary

B.

Surface

C.

Viscosity

D.

Cohesion

Correct answer is C

Viscosity, resistance of a fluid (liquid or gas) to a change in shape, or movement of neighboring portions relative to one another. Viscosity denotes opposition to flow. The reciprocal of the viscosity is called the fluidity, a measure of the ease of flow. Molasses, for example, has a greater viscosity than water. Because part of a fluid that is forced to move carries along to some extent adjacent parts, viscosity may be thought of as internal friction between the molecules; such friction opposes the development of velocity differences within a fluid. Viscosity is a major factor in determining the forces that must be overcome when fluids are used in lubrication and transported in pipelines. It controls the liquid flow in such processes as spraying, injection molding, and surface coating.