JAMB Physics Past Questions & Answers - Page 233

1,161.

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

1,162.

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

1,163.

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

1,164.

A force of 100N stretches an elastic string to a total length of 20cm. If an additional force of 100N stretches the string 5cm further, Find the natural length of the string

A.

15cm

B.

12cm

C.

10cm

D.

8cm

E.

5cm

Correct answer is A

Using, f1 = f2

e1 = 20 - L ; e2 = 5cm

\(\frac{f_1}{e_1}\) = \(\frac{f_2}{e_2}\)

\(\frac{100}{20 - L}\) = \(\frac{100}{5}\)

hence, L = 15cm