JAMB Physics Past Questions & Answers - Page 466

2,326.

When temperature of a liquid increases, its surface tension

A.

Decreases

B.

Increases

C.

Remain Constant

D.

Increases then decreases

Correct answer is A

No explanation has been provided for this answer.

2,327.

A solid weigh 10 .00 N in air, 6 N when fully immersed in water and 7 . 0 N 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

Correct answer is C

R.D = loss in weight in liquid X loss in weight in water.

R.D = (10 - 7)/(10 - 6) = 3/4

2,328.

If the stress on a wire is 107NM-2 and 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 104 Nm-2

B.

5 . 0 x 105 Nm-2

C.

2 . 0 x 108 Nm-2

D.

2 . 0 x 109 Nm-2

Correct answer is D

Y = stress/strain, but stress = 107Nm-2 (given).

Strain = e/l0. = (10.05 - 10.00)/10.00 = 0.005

Thus Y = 107/0.005 = 2 . 0 x 109Nm-2

2,329.

When the brakes in a car are applied, the frictional force force on the tyres is

A.

is a disadvantage because it is in the direction of the motion of the car

B.

is a disadvantage because it is in the opposite direction of the motion of the car

C.

is an advantage because it is in the direction of the motion of the car

D.

is an advantage because it is in the opposite direction of the motion of the car

Correct answer is D

No explanation has been provided for this answer.

2,330.

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

A.

1 . 25 x 104 W

B.

2 . 50 x 104 W

C.

1 . 25 x 106W

D.

2 . 50 x 106 W

Correct answer is B

Power = Force x \(\frac{distance}{time}\) = \(\frac{m(v - u)}{t} \times v\)

\(\frac{800(25 - 0)}{20} \times 25\)

= 2.5 x 10\(^{4}\) watts