WAEC Physics Past Questions & Answers - Page 9

41.

The basic principle of operation of a beam balance is-----------------

A.

Hooke's law

B.

Archimedes principle

C.

law of flotation

D.

principle of moments

Correct answer is D

Hooke's Law states that the extension of a spring is proportional to the load that is applied to it. A variety of materials obey this law as long as the load does not exceed the material's elastic limit.

Archimede's Principle states that a body immersed in a fluid experiences an upthrust equal to the weight of the fluid displaced, and this is fundamental to the equilibrium of a body floating in still water.

When a body floats in a liquid, the weight of the liquid displaced by its immersed part is equal to the total weight of the body. This is the law of floatation.

The Principle of Moments states that when a body is balanced, the total clockwise moment about a point equals the total anticlockwise moment about the same point.

42.

Using venier calipers, which of the following readings gives the correct measurement for the length of a rod?

A.

4.1 cm

B.

4.13cm

C.

125 cm

D.

1254 cm

Correct answer is B

Vernier calipers commonly used in industry provide a precision to 0.01 mm (10 micrometres), or 0.01cm or one thousandth of an inch.

 Usually, it is the total length of the main scale. Vernier calipers, generally, have a range of 300 mm

300 millimeters equal 30.0 centimeters (300mm = 30.0cm).

43.

The viscosity of a fluid depends on the following factors except the?

A.

relative motion between the layers of the fluid

B.

nature of the material of the fluid

C.

surface area of the fluid in contact

D.

normal reaction in the fluid

Correct answer is D

The viscosity of a material is affected by temperature, pressure, nature of fluid, velocity gradient

44.

Molecules move in random motion within a liquid. The total internal energy of the liquid depends on all of the following except its?

A.

temperature

B.

mass

C.

specific heat capacity

D.

melting point

Correct answer is D

Internal energy is affected by factors such as pressure, volume, and temperature.

All of the variables in this list are state functions. Mass, volume, pressure, temperature, density, and entropy are all examples of state functions.

45.

A small object of mass 50 g is released from a point A. Determine the velocity of the object when it reaches a point B, a vertical distance of 30m below A. [g = 10 ms\(^{-2}\)

A.

1.5 ms\(^{-1}\)

B.

6.0 m s\(^{-1}\)

C.

17.3 m s\(^{-1}\)

D.

24.5 m s\(^{-1}\)

Correct answer is D

v = ?, u = 0, a = 10, s = 30

V² = U²+2as
V² = 0 + 2 * 10 * 30
V² = 0 + 600
V = √600
V = 24.5m/s