## Physics 2021 Past Questions | JAMB

Study the following Physics past questions and answers for JAMBWAEC  NECO and Post-JAMB. Get prepared with official past questions and answers for upcoming examinations.

16. If the fraction of the atoms of a radioactive material left after 120 years is 1/64, what is the half-life of the material?

• A. 24 years
• B. 20 years
• C. 10 years
• D. 2 years

17. A certain radioactive source emits radiation that was found to be deflected by both magnetic and electric and electric fields. The radiation is?

• A. beta rays
• B. gamma rays
• C. x-rays
• D. ultra-viola rays

18. The inner diameter of a test tube can be measured accurately using a—-

• A. micrometer screw gauge
• B. pair of dividers
• C. meter rule
• D. pair of vernier calipers

19.  Two bodies have masses in the ratio3:1. They experience forces that impart to their acceleration in the ratio2:9 respectively. Find the ratio of forces the masses experienced

• A. 1:4
• B. 2:1
• C. 2:3
• D. 2:5

20. Particles of mass 10−2kg is fixed to the tip of a fan blade which rotates with angular velocity of 100rad−1. If the radius of the blade is 0.2m, the centripetal force is?

• A. 2N
• B. 20N
• C. 200N
• D. 400N

21.  A lead bullet of mass 0.05kg is fired with a velocity of 200ms−1into a block of mass 0.95kg. Given that the lead block can move freely, the final kinetic energy after impact is?

• A. 50J
• B. 100J
• C. 150J
• D. 200J

22.  A ball of mass 0.1kg is thrown vertically upwards with a speed of 10ms−1from the top of a tower 10m high. Neglecting air resistance, its total energy just before hitting the ground is? (Take g = 10ms−2)

• A. 5J
• B. 10J
• C. 15J
• D. 20J

23. A car of mass 800kg attains a speed of 25m/s in 20secs. The power developed in the engine is

• A. 1.25 x 104W
• B. 2.50x 104W
• C. 1.25 x 106W
• D. 2.50 x 106W

24. When the breaks in a car are applied, the frictional force on the tyre is?

• A. a disadvantage because it is in the direction of the motion of the car
• B. a disadvantage because it is in the opposite direction of the motion of the car
• C. an advantage because it is in the direction of the motion of the car
• D. an advantage because it is in the opposite direction of the motion of the car

25. If the stress on a wire is 107NM−2and the wire is stretched from its original length of 10.00 cm to 10.05 cm. The young’s modulus of the wire is?

• A. 5.0 x 10−4Nm−2
• B. 5.0 x 10−5Nm−2
• C. 2.0 x 10−8Nm−2
• D. 2.0 x 10−9Nm−2

26. A solid weighs 10.00N in air, 6N when forcefully immersed in water, and 7.0N when fully immersed in a liquid, X. Calculate the relative density of the liquid X.

• A. 5/3
• B. 4/3
• C. 3/4
• D. 7/10

27. When the temperature of a liquid increases, its surface tension

• A. decreases
• B. increases
• C. remains constant
• D. increases then decreases

28.  of its volume. What will be its pressure if the magnitude of its original temperature T is constant?

• A. p0/5
• B. 4p0/5
• C. p0
• D. 5P0

29.  A piece of substance of specific head capacity 450Jkg−1k1falls through a vertical distance of 20m from rest. Calculate the rise in temperature of the substance on hitting the ground when all its energies are converted into heat. [g = 10ms−2]

• A. 29ºC
• B. 49ºC
• C. 92ºC
• D. 94ºC

30.  A liquid boils when its saturated vapor pressure is equal to the external pressure
II. Dissolved substances in pure water lead to an increase in the boiling point.
III. When the external pressure is increased, the boiling point increases.
IV. Dissolved substances in pure water decreases the boiling point

Which of the above combinations are peculiarities of the boiling point of a liquid?

• A. I, II and III only
• B. I, II, III, and IV
• C. I, II, and IV
• D. II, III, and IV
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