Question 451:

• JAMB 1987

The vacuum in a thermos flask helps to reduce heat transfer by?

A. Convection and radiation
B. Convection and conduction
C. Conduction and radiation
D. Radiation only

Question 452:

• JAMB 1987

Which of the following phenomena explains the fact that a house whose roof is coated with white paint will be cooler in the hot season than one coated with black paint ?

A. Conduction
B. Convection
C. Refraction
D. Reflection

Question 453:

• JAMB 1987

Calculate the amount of heat required to convert 2kg of ice at 2^oC to water at 0^oC. [specific heat capacity of ice = 2090Jkg^-1oC^-1, specific latent heat of fusion of ice = 333kJkg^-1]

A. 666J
B. 8360J
C. 666 000J
D. 674 360J

Question 454:

• JAMB 1987

A wave has a frequency of 2Hz and a wavelength of 30cm. The velocity of the wave is

A. 60.0ms^-1
B. 6.0ms^-1
C. 1.5ms^-1
D. 0.6ms^-1

Question 455:

• JAMB 1987

A boat at anchor is rocked by waves whose crest are 100m apart and whose velocity is 25ms^-1. At what interval does the wave crest reach the boat?

A. 2500.00s
B. 75.00s
C. 4.00s
D. 0.25s