If an object is placed in front of two mirrors inclined at 90o, how many images will be formed?
- A. five
- B. four
- C. three
- D. two
When the length I of a piece of wire under constant tension is varied, the relationship of the frequency of the vibration f\(\alpha\)/ is
- A. f\(\alpha\)/
- B. f\(\alpha \frac{1}{I^2}\)
- C. f \(\alpha\sqrt I\)
- D. f\(\alpha \frac{1}{1}\)
Which of the following statements supports the assumption that light travels in straight lines?
- A. light can be diffracted
- B. a source of light produces distinct shadows of opaque objects
- C. a source of light produces interference patterns on a suitably placed screen
- D. light can be reflected
The lowest note emitted by a stretched string has a frequency of 40Hz. How many overtones are there between 40Hz and 150Hz?
- A. 1
- B. 2
- C. 3
- D. 4
Which of the following instruments has a pure tone?
- A. guitar
- B. vibrating strings
- C. tuning fork
- D. siren
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
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
Calculate the amount of heat required to convert 2kg of ice at 2oC to water at 0oC. [specific heat capacity of ice = 2090Jkg-1 oC-1, specific latent heat of fusion of ice = 333kJkg-1]
- A. 666J
- B. 8360J
- C. 666 000J
- D. 674 360J
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
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
In which of the following are the substance arranged in descending order of their thermal conductivities?
- A. copper, steel, glass
- B. steel, copper, glass
- C. steel, glass, copper
- D. copper, glass, steel
22,000J of heat is required to raise the temperature of 1.5kg of paraffin from 20oC to 30oC. Calculate the specific heat capacity of paraffin.
- A. 1466Jkg-1 oC-1
- B. 2933Jkg-1 oC-1
- C. 4400Jkg-1 oC-1
- D. 5866Jkg-1 oC-1
Hot water is added to three times its mass of water at 10oC and the resultant temperature is 20oC. What is the initial temperature of the hot water?
- A. 100oC
- B. 80oC
- C. 50oC
- D. 40oC
As a result of air at the top of a barometer, the height of the mercury column is 73.5cm when it should be 75.0cm; the volume of the space above the mercury is 8.0cm3. Calculate the correct barometer height when the barometer reads 74.0cm and the volume of the space above the mercury is 6.0cm3.
- A. 72.0cm
- B. 74.5cm
- C. 75.1cm
- D. 76.0cm
The length of a side of a metallic cube at 20oC is 5.0cm. Given that the linear expansivity of the metal is 4.0 x 10-5k-1, find the volume of the cube at 120oC .
- A. 126.50cm3
- B. 126.25cm3
- C. 126.00cm3
- D. 125.00cm3
The distance between the fixed points of a centigrade thermometer is 20cm. What is the temperature when the mercury level is 4.5cm above the lower mark?
- A. 22.5oC
- B. 29.0oC
- C. 90.0oC
- D. 100.0oC
A cube of side 10cm and mass 0.5kg floats in a liquid with only \(\frac{1}{5}\) of its height above the liquid surface. What is the relative density of the liquid?
- A. 0.125
- B. 0.250
- C. 0.625
- D. 2.500
A load of 5N gives an extension of 0.56cm in a wire which obeys Hooke’s law. What is the extension caused by a load of 20N?
- A. 1.12cm
- B. 2.14cm
- C. 2.24cm
- D. 2.52cm
The mechanical advantage(MA) of an inclined plane depends on
- A. its length
- B. its height
- C. the product of its length and height
- D. the ratio of its length to its height
If a beaker is filled with water it is observed that the surface of the water is not horizontal at the glass-water interface. This behavior is due to
- A. friction
- B. viscosity
- C. surface tension
- D. evaporation
The coefficient of static friction between a 40kg crate and concrete surface is 0.25. Find the magnitude of the minimum force needed to keep the crate stationary on the concrete base inclined at 45o to the horizontal. [G = 10ms-1]
- A. 400N
- B. 300N
- C. 283N
- D. 212N