# 1993 - JAMB Physics Past Questions and Answers - page 1

1

Which of the following quantities has the same unit as the watt?

A

Force x time

B

Force x distance

C

Force x acceleration

D

Force x velocity

**correct option:**d

2

The external and internal diameter of a tube are measured as (32 ± 2)mm and (21 ± 1)mm respectively. Determine the percentage error in the thickness of the tube.

A

27%

B

14%

C

9%

D

3%

**correct option:**c

Actual thickness = 34 - 22 = 12

error thickness = 30 - 20 = 10

error = 12 - 10 = 2mm that is, (11 ± 1)mm

%error = \(\frac{1}{11}\) x \(\frac{100}{1}\)

= 9%

Users' Answers & Commentserror thickness = 30 - 20 = 10

error = 12 - 10 = 2mm that is, (11 ± 1)mm

%error = \(\frac{1}{11}\) x \(\frac{100}{1}\)

= 9%

3

Two forces of magnitudes 7N and 3N act at right angles to each other. The angle \(\theta\) between the resultant and the 7N force is given by

A

cos\(\theta\) = \(\frac{3}{7}\)

B

sin\(\theta\) = \(\frac{3}{7}\)

C

tan\(\theta\) = \(\frac{3}{7}\)

D

cot\(\theta\) = \(\frac{3}{7}\)

4

A rocket burns fuel at the rate of 10kgs

^{-1}and ejects it with velocity of 5 x 10^{3}ms^{-1}. The thrust exerted by the gas on the rock isA

2.5 x 10

^{7}NB

5.0 x 10

^{4}NC

5.0 x 10

^{2}ND

2.0 x 10

^{-3}N**correct option:**b

Thrust = \(\frac{\text{mass x velocity}}{time}\)

= 10 x 5 x 10

= 5.0 x 10

Users' Answers & Comments= 10 x 5 x 10

^{3}= 5.0 x 10

^{4}N5

The force experienced by an object of mass 60.0kg in the moon's gravitational field is 1.002 x 10

^{2}N. What is the intensity of the gravitational field?A

0.60Nkg

^{-1}B

1.67Nkg

^{-1}C

6.12 x 10

^{2}Nkg^{-1}D

9.81ms

^{-2}**correct option:**b

Intensity = \(\frac{1.002 \times 102}{60}\)

= 1.67Nkg

Users' Answers & Comments= 1.67Nkg

^{-1}6

Which of the following correctly describes the energy changes in the generation of light by a hydroelectric power station?

A

Electrical \(\to\) mechanical \(\to\) potential

B

potential \(\to\)mechanical \(\to\)electrical \(\to\) light

C

mechanical \(\to\) sound \(\to\) electrical \(\to\) light

D

kinetic \(\to\) mechanical \(\to\) electrical \(\to\)light

**correct option:**b

7

A plane inclined at angle \(\theta\) has a velocity ratio of 10 : 1. The inclination of the plane to the horizontal is given by

A

tan\(\theta\) = \(\frac{1}{10}\)

B

cot\(\theta\) = \(\frac{1}{10}\)

C

cos\(\theta\) = \(\frac{1}{10}\)

D

sin\(\theta\) = \(\frac{1}{10}\)

8

A weightless vessel of dimensions 4m x 3m x 2m is filled with a liquid of density 1000kgm

^{-3}and sealed. What is the maximum pressure this container can exert on a flat surface? [g = 10ms^{-2}]A

9 x 10

^{4}NM^{-2}B

4 x 10

^{4}NM^{-2}C

3 x 10

^{4}NM^{-2}D

2 x 10

^{4}NM^{-2}9

An object of mass 400g and density 600kgm

^{-3}is suspended with a sting so that half of it is immersed in paraffin of density 900kgm^{-3}. The tension in the string isA

1.0N

B

3.0N

C

4.0N

D

5.0N

**correct option:**b

volume of object = \(\frac{400 \times 10^{-2}}{600}\)

= 0.00067m

volume of paraffin displaced = \(\frac{1}{2}\) x 0.00067

= 0.00034m

mass of paraffin = 900 x 34 x 10

= 0.3kg

weight of paraffin = 0.3 x 10

= 3N = upthrust = tension in the string

Users' Answers & Comments= 0.00067m

^{3}volume of paraffin displaced = \(\frac{1}{2}\) x 0.00067

= 0.00034m

^{3}mass of paraffin = 900 x 34 x 10

^{-5}= 0.3kg

weight of paraffin = 0.3 x 10

= 3N = upthrust = tension in the string

10

The thermometric properties of the thermocouple is that is

A

e.m.f. changes with temperature

B

resistance changes with temperature

C

volume changes with temperature

D

pressure changes with resistance

**correct option:**a