Physics questions and answers

Physics Questions and Answers

If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.

2,826.

A bridge made of steel is 600m long. What is the daily variation in its length if the night-time and daytime temperatures are 10°C and 35°C respectively. The linear expansivity of steel is 0.000012C\(^{-1}\).

A.

0.18cm

B.

1.80cm

C.

18.00cm

D.

1800cm

Correct answer is C

\(\alpha\) = \(\frac{extension}{L\Delta\theta}\)

0.000012 = \(\frac{e}{600 \times (35 - 10}\)

= 0.18m

= (0.18 x 100) cm

= 18.0 cm

2,827.

A platinum resistance thermometer wire has a resistance of 5 ohms at 0oC and 5.5 ohms at 100oC. Calculate the temperature of the wire when the resistance is 5.2 ohms

A.

80oC

B.

60oC

C.

40oC

D.

10oC

Correct answer is C

100oC .... 5.5

\(\theta\)oC .... 5.3

0oC .... 5.0

\(\frac{\theta - 0}{100 - 0}\) = \(\frac{5.5 - 5 .0}{5.5 - 5.0}\)

\(\theta\) = 40oC

2,828.

If a plastic sphere floats in water (density = 1000kgm3) with 0.5 of its volume submerged, and floats in oil with 0.4 of its volume submerged the density of the oil is

A.

800kgm3

B.

1200kgm3

C.

1250kgm3

D.

2000kgm3

Correct answer is A

R.d = \(\frac{0.4}{0.5}\) = 0.8

0.8 = \(\frac{\text {Density of oil}}{\text{Density of water}}\)

0.8 = \(\frac{\text {Density of oil}}{1000}\)

Density of oil = 800kgm3

2,829.

In an experiment to determine Young's Modulus for a wire, several loads are attached to the wire and the corresponding extension measured. The tensile stress in each case depends on the

A.

load and the extension

B.

load and the radius of the wire

C.

radius of the wire and the extension

D.

extension and the original length of the wire

Correct answer is B

No explanation has been provided for this answer.