JAMB Physics Past Questions & Answers - Page 238

1,187.

A thin aluminum plate has a surface area of 1500m at 20oC. What will be its surface area when it is cooled to -20oC? (Take the linear expansivity of aluminum to be 2.5 x 10-5k-1).

A.

1.503m2

B.

1.500m2

C.

1.498m2

D.

1.497m2

E.

1.490m2

Correct answer is C

\(\beta\) = A2 - A1

2 X 10-5 x 2.5 = \(\frac{A_2 \times 1.5}{1.5 \times (-20 -20)}\)

A2 = 1.498m2

1,188.

A uniform cylindrical block of wood floats in water with one-third of its height above the water level, in a liquid of relative density 0.8, what fraction of its height will be above the liquid level?

A.

\(\frac{1}{6}\)

B.

\(\frac{1}{5}\)

C.

\(\frac{1}{3}\)

D.

\(\frac{4}{5}\)

E.

\(\frac{5}{6}\)

Correct answer is E

Height inside H2O = \(\frac{2}{3}\)

R.d = \(\frac{\text{height inside}H_2O}{\text{height inside liquid}}\)

0.8 = \(\frac{\frac{2}{3}}{X}\)

1,189.

A metal cube of volume 103mm3 is lowered into a measuring cylinder containing water. If the internal cross-sectional area of the cylinder is 1.5 x 102mm2, by how much does the water level rise in the cylinder?

A.

6.67 x 100mm

B.

8.50 x 102mm

C.

1.15 x 103mm

D.

2.50 x 103mm

E.

1.50 x 105mm

Correct answer is A

Height = \(\frac{volume}{area}\)

= Height = \(\frac{10^3}{1.5 \times 10^2}\)

= 6.67mm

1,190.

The areas of the effort and load pistons of a hydraulic press are 0.5m2 and 5m2 respectively. If a force F1 of 100N is applied on the effort piston, the force F2 on the load is

A.

10N

B.

100N

C.

500N

D.

1000N

E.

5000N

Correct answer is D

\(\frac{load}{area}\) = \(\frac{effort}{area}\)

\(\frac{load}{5}\) = \(\frac{100}{0.5}\)

load = 1000N