JAMB Physics Past Questions & Answers - Page 155

771.

A particle of weight 120N is placed on a plane inclined at 300 to the horizontal. If the plane has an efficiency of 60% to the floor what is the force required to push the weight uniformly up the plane?

A.

50N

B.

100N

C.

175N

D.

210N

Correct answer is B

Efficiency = \( \frac{W(120N)INPUT}{WORK OUTPUT} \times \frac{100}{1} \)

And for incline plane

V.R =\( \frac{1}{Sin\theta} \\
= V.R = \frac{1}{Sin30} =\frac{1}{0.5} = 2 \\

\text{therefore } \frac{60}{120} = \frac{M.A}{2}
=M.A = \frac{120}{100} = 1.2\\

\text{but M.A } = \frac{load}{effort} = \frac{120}{E}\\

\text{therefore} \frac{120}{E} = 1.2 \\

= E =\frac{120}{1.2 } = 100N \\ \)


Therefore Effort up the plane = 100N

772.

An alternating current with a frequency of 100HZ has a period of

A.

0.03sec

B.

0.01sec

C.

0.04sec

D.

0.15sec

Correct answer is B

F = 100HZ, period, T = 1/f = 1/100

= 0.01 sec

The period (T) = 0.01sec

773.

Momentum and Kinetic energy are conserved in

A.

Inelastic collision

B.

Elastic collision

C.

Explosion

D.

Spacecraft

Correct answer is B

Momentum and kinetic energy are conversed in elastic collision

774.

The property of a body to remain at rest or to continue to move in a straight line is known as

A.

force

B.

Impulse

C.

Energy

D.

Inertia

Correct answer is D

Inertia: the property of a body that resists any change to its uniform motion, equivalent to its mass

775.

The normal temperature of human body is record at what ranges?

A.

27°C to 43°C

B.

30°C to 40°

C.

98.4°C only

D.

Between 35°C to 37°C

Correct answer is D

The range of temperature is between 35°C and 43°C but for normal temperature of human body is between the range of 35°C to 37°C respectively