JAMB Physics Past Questions & Answers - Page 214

1,066.

A heater marked 50W will evaporate 0.005kg of boiling water in 50 seconds. The specific latent heat of vaporization of water in J/kg is

A.

5.0 x 106

B.

1.0 x 106

C.

2.5 x 106

D.

2.5 x 105

E.

5.0 x 105

Correct answer is E

Heat energy = Electrical energy

mL = power x time

0.005 x L = 50 x 50

L = 5 x 105J/kg

1,067.

Which of the following statements is true of a body which is moving in a straight line with uniform acceleration? The velocity of the body

A.

is also uniform

B.

must always be zero when the body stops accelerating

C.

will increase with time in the direction of the acceleration

D.

is equal to the quotient of distance travelled and time

E.

is the product of the distance travelled and time

Correct answer is C

No explanation has been provided for this answer.

1,068.

A rocket burns 0.01kg of fuel each second and ejects it as a gas with a velocity of 5,000m/s. What force does the gas exert on the rocket?

A.

500,000N

B.

500N

C.

50N

D.

5,000N

E.

50,000N

Correct answer is C

F =\(\frac{m(v - u)}{T}\)

= \(\frac{0.01(5000 - 0)}{1}\)

= 50N

1,069.

Which of the following statements is NOT true of \(\gamma\)-rays?

A.

\(\gamma\)-rays belong to the electromagnetic spectrum

B.

\(\gamma\)-rays do not carry an electron charge

C.

\(\gamma\)-rays obey the inverse cube law in air

D.

the thickness of aluminium which stops b-particule has a negligible effect on \(\gamma\)-radiation

E.

the difference between \(\gamma\)-rays and X-rays is that \(\gamma\)-rays originate from energy charges in the nuclei of atoms, while X-rays comes from energy charges associated with the electron structure of atoms

Correct answer is C

No explanation has been provided for this answer.

1,070.

As a positively charge rod is brought nearer to the top cap of a positively charged gold leaf electroscope, the divergence of the leaves will

A.

decrease to zero

B.

steadily increase

C.

decrease to zero and then increase

D.

remain constant

E.

increase to a maximum and then decrease

Correct answer is B

No explanation has been provided for this answer.