JAMB Physics Past Questions & Answers - Page 217

1,081.

A mango fruit drops from a branch 10m above the ground, just before hitting the ground its velocity is (g = 10ms-2)

A.

10√2ms-1

B.

10ms-1

C.

100ms-1

D.

5√2ms-1

E.

200ms-1

Correct answer is A

Using, V2 = U2 + 2gs

V2 = 02 + (2 x 10 x 10)

V = 10√2ms-1

1,082.

The force responsible for holding the moon in its orbit around the earth against the gravitational pull of the earth is

A.

centrifugal

B.

rotational

C.

reaction

D.

centripetal

E.

tractional

Correct answer is D

No explanation has been provided for this answer.

1,083.

An electric iron is rated at 1000watts, 250v. The corresponding maximum resistance and accompanying current is

A.

62.5A, 4.0\(\Omega\)

B.

16.0A, 62.5\(\Omega\)

C.

62.5A, 16.0\(\Omega\)

D.

4.0A, 62.5\(\Omega\)

E.

4.0A, 250\(\Omega\)

Correct answer is D

R = \(\frac{V^2}{R}\) = IV ; R = \(\frac{V^2}{P}\) and I = \(\frac{P}{V}\)

R = \(\frac{(250)^2}{100}\) and I = R = \(\frac{1000}{250}\)

R = 62.5\(\Omega\) and I = 4A

1,084.

The echo of a sounder from the bottom of an ocean is heard 2.5 seconds later. If the speed of sound in water is 1,400ms-1, the depth of the ocean is

A.

1,750m

B.

3,500m

C.

1,400m

D.

2,800m

E.

2,100m

Correct answer is A

No explanation has been provided for this answer.

1,085.

The tyre pressure of a car was found to be 150cmHg in the morning at a temperature of 27°C. Hard driving in the afternoon raised the temperature of the tyres to 57°C. The tyre pressure by the afternoon would be?

A.

increased by 15.0cm Hg

B.

decreased by 15.0cm Hg

C.

increased by 22.50cm

D.

decreased by 22.50cm Hg

E.

remained constant

Correct answer is A

\(\frac{P_1}{T_1}\) = \(\frac{P_2}{T_2}\) at constant volume

\(\frac{150}{27 + 273}\) = \(\frac{P_1}{57 + 273}\)

P2 = 165cmHg