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JAMB Physics Past Questions & Answers - Page 91

452.

An object of volume 400cm3 and 2.5gcm-3 is suspended from a spring balance with half its volume immersed in water. Determine the reading on the spring balance. (Density of water = 1gcm-3)

A.

1200g

B.

1000g

C.

800g

D.

400g

Correct answer is C

Mass = density x volume

400 x 2.5 = 1000g

Loss in mass = volume x density

= 4002 x 1 = 200g

Reading on spring balance = 1000 - 200g = 800g

453.

Which of the following substances lowers the surface tension of water?

A.

metal

B.

sand

C.

detergent

D.

paper

Correct answer is C

No explanation has been provided for this answer.

454.

A ball is dropped from the top of a tower. Due to air resistance,it reaches terminal velocity. Which of the following statement(s) about its motion is/are correct? i. The acceleration of the ball is zero. ii. The net force on the ball is zero. iii. The velocity of the ball increases.

A.

i only

B.

i and ii only

C.

ii and iii only

D.

i, ii and iii

Correct answer is B

Terminal velocity refers to the constant speed that an object reaches as it falls through a liquid or gas.

Since the net force on the object is zero, the object has zero acceleration.

455.

The diagram given, represents the graph of stress against strain for an elastic wire. The point Q on the graph is the

A.

elastic limit

B.

breaking point

C.

yield point

D.

proportional limit

Correct answer is B

No explanation has been provided for this answer.