1) The inner diameter of a test tube can be measured accurately using a?
- A. micrometer screw guage
- B. pair of dividers
- C. metre rule
- D. pair of vernier calipers
View Correct Answer
Correct Answer: Option D
Explanation
A Vernier caliper is an instrument used to measure both the outer and inner diameters of a tube.
2) Two bodies have masses in the ratio 3:1. They experience forces which impart to them acceleration in the ratio 2:9 respectively. Find the ratio of forces the masses experienced.
- A. 1 : 4
- B. 2 : 1
- C. 2 : 3
- D. 2 : 5
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Correct Answer: Option C
Explanation
Let the forces be F1, and F2.
F1 = m1 a1 = 3 x 2 = 6N
F2 = m2 a2 = 1 x 9 = 9N
F1 : F2 = 6:9 = 2:3
Thus ratio of forces is 2: 3
3) 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. 2 N
- B. 20 N
- C. 200 N
- D. 400 N
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Correct Answer: Option B
Explanation
Centripetal Force (Fc) = mv2/r
= mω2/r
(Since V = ωr)
F = 100 x 0.2
F =20 N
4) A lead bullet of mass 0.05kg is fired with a velocity of 200ms−1
into a lead block of mass 0.95kg. Given that the lead block can move freely, the final kinetic energy after impact is
- A. 50 J
- B. 100 J
- C. 150 J
- D. 200 J
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Correct Answer: Option A
Explanation
From principle of conservation of linear momentum,
(0.05 x 200) + (0.95 x 0) = (0.05 + 0.95) x V (since collision is inelastic).
10 + 0 = V
Thus V = 10m/s.
Recall Kinetic Energy = 1/2mv2
∴∴ K.E = 1/2 (0.05 + 0.95) x 1022
K.E = 1/2 (1 x 100) = 50 J.
5) A ball of mass 0.1kg is thrown vertically upwards with a speed of 10ms-1 from the top of a tower 10m high. Neglecting air resistance, its total energy just before hitting the ground is (take g = 10ms-2)
- A. 5 J
- B. 10 J
- C. 15 J
- D. 20 J
View Correct Answer
Correct Answer: Option C
Explanation
Height h = 1/2 (U2/g) = 102/20 = 5m
Energy before hitting ground is = P.E at the height of 5m.
P.E = mgh = 0.1 x 10 x 10= 10 J
K.E = 1/2 MV2 = 5J
T.E = K.E + P.E = 5 + 10 = 15J
