Physics 2010 JAMB Past Questions

Physics 2010 JAMB Past Questions

1.Two cars moving in the same direction have speeds of 100 kmh^-1 and 130 kmh^-1 what is the velocity of the faster car as measured by an observer in the slower car?

• A. 30 kmh^-1
• B. 130 kmh^-1
• C. 200 kmh
• D. 230 kmh^-1

Correct Answer: Option A

Explanation

Since the cars are moving in the same direction, the velocity of a body A, V_a,relative to another body B, V_b is given by V = V_a - V_b
∴ the velocity of faster car is measured by the observer in the slower car is V = 130kmh^-1 - 100 kmh^-1 = 30 kmh^-1

 

 

2. A stone and a feather are dropped from the same height above the earth surface. ignoring air resistance, which of the following is correct?

• A. the feather will be brown away by the wind while stone will drop steadily
• B. the stone and the feather will both reach the ground a the same time
• C. the feather will reach the ground first
• D. the stone will reach the ground first

Correct Answer: Option B

Explanation

The acceleration of free fall due to gravity is independent of mass of the body. Therefore, ignoring air resistance, which affects feather more than the stone, the stone and the feather will both reach the ground at the same time

 

3. A car moves with an initial velocity of 25 ms^-1 and reaches a velocity of 45 ms^-1 in 10s. what is the acceleration of the car?

• A. 2 ms^-2
• B. 5 ms^-2
• C. 20 ms^-2
• D. 25 ms^-2

 Correct Answer: Option A

Explanation

Acceleration = (increase in velocity)/time taken
= (45 - 25)/10 = (20)/10 = 2ms^-2

 

 

4. The surfaces of conveyor belts are made rough so as to

• A. protect them while carrying loads
• B. prevent the loads from slipping
• C. enable them to carry more load
• D. make them stronger

Correct Answer: Option B

Explanation

Rough surface promotes friction. Therefore, roughness of conveyor belt prevents the load from slipping

 

 

5. A machine of velocity ratio 6 requires an effort of 400 N to raise a load of 800 N through I m. Find the efficiency of the machine

• A. 55. 6 %
• B. 50.0%
• C. 33.3%
• D. 22.2%

Correct Answer: Option C

Explanation

Efficiency = (MA)/V.R x 100% = (load)/Effort x (1)/V.R
= (800)/400 x (1)/6 x 100% = 33.3%

 

6. If a wire 30 cm long is extended to 30.5 cm by a force of 300 N. find the strain energy of wire

• A. 0.75 J
• B. 7.50 J
• C. 75.00 J 
• D. 750.00 J

Correct Answer: Option A

Explanation

Energy stored in a stretched wire (strain energy)
= average force x extension
= (1)/2 Fe
= (1)/2 x 300 N (30.5 - 30.0) x 10^-2 m
= (300)/2 x 0.5 x 10^-2 = 0.75J

 

 

7. In a hydraulic press, the pump piston exerts a pressure of 100 pa on the liquid. what force is exerted in the second piston of cross sectional area 3 m²?

• A. 300 N
• B. 200 N
• C. 150 N
• D. 100 N

Correct Answer: Option A

Explanation

Thrust = pressure x area = 100 pa x 3 m² = 300 N

 

 

8. The accurate measurement of the relative density of a substance in its powdered form is done with a beam balance and

• A. a density bottle
• B. an eureka can
• C. a pipette
• D. a burette

Correct Answer: Option A

Explanation

Since relative density = mass of substance
mass of equal volume of water relative density bottle should be used to determine the mass of the substance, and mass of an equal volume of water by filling the bottle with the powder and water respectively and weighed with the beam balance.

 

 

9. A hydrometer is an instrument used in measuring

• A. vapour pressure of a fluid
• B. density of liquid
• C. relative humidity of a liquid
• D. relative density of a liquid

Correct Answer: Option D

Explanation

The instrument used in measuring relative density is hydrometer

 

10. One special advantage of alcohol over mercury as a thermometric liquid is its

• A. low density
• B. low freezing point
• C. high specific
• D. low boiling point

Correct Answer: Option B

Explanation

The low freezing point of alcohol, -115°c enable low temperatures to be measured. mercury freezes at 39°c, and cannot be used in countries like Russia where winter temperatures of -40°c are common

 

 

11. The density of a certain oil on frying becomes 0.4 kgm−3

with the volume of 20m3. what will be its initial volume when its initial density is 0.8 kgm−3

assuming no loss of oil due to spillage?

• A. 12m³
• B. 10m³
• C. 8m³
• D. 5m³ 

Correct Answer: Option B

Explanation

Density (D) = massvolume
∴Mass=Density×volume
= 0.4×20=8kg
The initial volume = MassInitial density
=

 

 

12. Heat is radiated by hot objects in the form

• A. x-rays
• B. light energy
• C. infrared rays
• D. solar energy

Correct Answer: Option C

Explanation

Inform falling on the skin causes the skin causes the sensation of warmth. since the objects are hot, the correct option is informed.

 

 

13. If a container is filled with ice to the brim, what happens to the level of water when the ice completely melts?

• A. the level of water goes up
• B. the water in the glass outflows
• C. the level of water remains unchanged
• D. the level of water drops 

Correct Answer: Option D

Explanation

Due to anomalous expansion of water at temperature range (0 - 4)°c, when a given mass of water turns into ice, its volume will increase, while the mass remains constant. Thus, when a given volum of ice melts, the volume of water formed will be less than the volume of ice. Hence, the level of water in the container will drop.

14. The small droplet of water that forms on the grass in the early hours of the morning is

• A. hail
• B. dew
• C. fog
• D. mist

Correct Answer: Option B

Explanation

Dew point is the temperature at which the water vapour present in air is just sufficient to saturate it. Dew is formed when air is cooled below its dew point

 

 

15.A vapour is said to be saturated when

• A. a dynamic equilibrium exists between liquid molecules and the vapour molecules
• B. a dynamic aquilibrium exists such that more molecules return to the liquid than are living it
• C. the temperature of the vapour varies
• D. the vapour pressure is atmospheric 

Correct Answer: Option A

Explanation

A saturated vapour is one which is in dynamic equilibrium with its own liquid; that is as many go from the liquid to the vapour state every second return back to liquid.
16. The pressure of one mole of an ideal gas of volume 10^-2 m³ at a temperature of 27°c is

[molar gas constant = 8.3 J mol^-1 k^-1]

• A. 2.49 x 10⁴ Nm^-2
• B. 2.24 x 10⁴ Nm^-2
• C. 2.49 x 10⁵ Nm^-1
• D. 2.24 x 10⁵ Nm^-1

Correct Answer: Option C

Explanation

T = 27 + 273 = 300 K, volume, V = 10^-2 m³ molar gass constant, R = 8.3 Jmol- 1k - 1 number of mole, n = 1
PV = NRT
i.e P = (NRT)/V = (1 x 8.3 x 300)/10^-2
= 2.49 x 10⁵ Nm^-1

 

 

17. Which of the following has no effect on radiation?

• A. nature of surface
• B. density
• C. surface area
• D. temperature

Correct Answer: Option B

Explanation

Radiation depends on nature of the surface area and temperature. It is independent of density.

 

 

18. The wavelength of a wave traveling with a velocity of 420 ms^-1 is 42 m. what is its period?

• A. 1.2 s
• B. 1.0 s
• C. 0.5 s
• D. 0.1 s

Correct Answer: Option D

Explanation

V = fλ
f = (v)/λ = (420)/42 = 10 HZ
Period, T = (1)/F = (1)/10 = 0.1 secs

 

 

19. The sound of an electricity bell dies down slowly when air is slowly pumped out from a bottle because

• A. the wavelength of sound becomes greater in the bottle
• B. sound cannot pass through the bottle
• C. sound needs a material medium
• D. sound can pass through a vacuum

Correct Answer: Option C

Explanation

Sound wave requires a material medium for its propagation. so when air is being pumped out the density of the medium is being reduced and the sound dies down. when all the air has been pumped out of the glass, no sound will be heard, as sound sound cannot travel through vacuum

 

 

20. During a thunderstorm, the sound is heard over a long time. this phenomenon is referred to as

• A. diffraction of sound
• B. refraction of sound
• C. superposition
• D. reveraberation

Correct Answer: Option D

Explanation

The lengthening effect of sound is known as reverberation.

 

21. In comparing the camera and the human eye, the film of the camera function as the

• A. retina
• B. iris
• C. cornea
• D. pupil

Correct Answer: Option A

Explanation

The retina is light sensitive layer living the inner wall of the eye where image is formed. in the camera, image is formed on a light sensitive film.

 

 

22. An object 4 cm high is placed 15 cm from a concave mirror of focal length 5 cm. The size of the image is

• A. 2 cm
• B. 3 cm
• C. 4 cm
• D. 5 cm 

 Correct Answer: Option A

Explanation

(1)/v + (1)/u = (1)/f
(1)/v + (1)/15 = (1)/5
(1)/v = (1)/5 - (1)/15 = (3 - 1)/15 = (2)/15
∴ v = (15)/2 = 7.5 cm
magnification = (v)/u = (image size)/object size
(7.5)/15 = (X)/4
∴ image size. X = (7.5 x 4)/15 = 2 cm

 

 

23. An object is embedded in a block of ice, 10 cm below the plane surface. if the refractive index of the ice is 1.50, the apparent depth below the surface is

• A. 2.50 cm
• B. 6.67 cm
• C. 7.50 cm
• D. 7.63 cm

Correct Answer: Option B

Explanation

Refraction index, n = (real depth)/apparent depth
1.5 = (10)/X
X = (10)/1.5 = 6.67 cm

 

 

24. Which of the following is used for the correction of short sightedness?

• A. convex lens
• B. concave lens
• C. convex mirror
• D. concave mirror 

Correct Answer: Option B

Explanation

Concave lens diverges parallel rays of light. A short sighted person has the image formed before the retina,and the rays have to be diverged so that they intersect to form image onto the retina

 

 

25. Dispersion occurs when white light passes through a glass prism because of the

• A. different hidden colours in the glass
• B. different speeds of the colour in the glass
• C. defects in the glass
• D. high density of the glass

Correct Answer: Option B

Explanation

Dispersion is the splitting of white light into its spectral component colours and is caused by different speed of the colours in the prisma