JAMB Physics Past Questions & Answers - Page 369

1,841.

A metal of volume 40 cm3 is heated from 30 °c to 90 °c, the increase in volume is

A.

0.12 cm3

B.

4.00 cm3

C.

1.20 cm3

D.

0.40 cm3

E.

no correct option

Correct answer is E

increase in volume, DV = RV1 ∆ θ = 3α Vsub>1 Dθ
= 3 x 2.0 X 10-5 x 40 x (90 - 30)
= 6 x 10-5 x 40 x 60
0.144 cm3
∴ No correct option

1,842.

An object weighs 22 kg in water and 30kg in air. what is the upthrust exerted by the liquid on the object.

[g = 10 ms2]

A.

50 N

B.

520 N

C.

220 N

D.

80 N

Correct answer is D

upthrust = weight in air - weight in liquid = 30 x 10 - 22 x 10 = 300 - 220 = 80 N

1,843.

If a tube of small radius opened at both ends is placed in a liquid, the liquid will

A.

remain at the same level irrespective of whether the liquid wet the glass or not

B.

fall below the liquid level if the liquid wets the glass

C.

falls below the liquid level if the liquid does not wet the glass

D.

rise above the liquid level if the liquid does not wet the glass

Correct answer is C

The liquid will rise up the capillary if it wets glass and falls below its wets glass and falls below its initial level if it does not wet glass

1,844.

A carpenter on top of a roof of 20.0m high dropped a hammer of mass 1.5 kg and it fell directly to the ground. the kinetic energy of the hammer just before hitting the ground is?

[g = 10 ms-2]

A.

600 J

B.

150 J

C.

300 J

D.

450 J

Correct answer is C

K e just before hitting the gound
= P e at the maximum height (conservation of mechanical energy)
K e = P e = mgh = 1.5 x 10 x 20
= 300 J

1,845.

An object of mass 2 kg moves with a velocity of 10 ms1 round at circle of radius 4 m. Calculate the centripetal force on the object

A.

25 N

B.

100 N

C.

50 N

D.

40 N

Correct answer is C

Centripetal force,
F = \( \frac{mv^2}{r} \)
= \( \frac{2 \times 10^2}{4} \)
= \( \frac{200}{4} \)= 50N