The S.I units of frequency, period and amplitude of a wave are respectively
- A. hertz, second and centimeter
- B. second, metre and hertz
- C. metre, hertz and seconds
- D. hertz, second and metre
The temperature of a liquid falls after some of it has evaporated because
- A. the liquid left is smaller in volume and the breeae easily cools it
- B. the more energetic molecules have escaped into the atmosphere
- C. the liquid left has less latent heat
- D. after evaporation impurites are left behind
A quantity of steam at 100oC condenses to water at the same temperature by releasing 6.9 x 104J of energy. Calculate the mass of the condensed steam. [specific latent heat of vaporization of eater = 2.3 x 106 J kg-1]
- A. 3.0 x 10-1 kg
- B. 3.0 x 10-2 kg
- C. 3.0 x 10-3 kg
- D. 3.0 x 10-4 kg
The amount of energy required to change a kilogram of ice in water without a change in temperature is
- A. heat capacity of ice
- B. specific heat capacity
- C. specific latent heat of vaporisation of ice
- D. specific latent heat of fusion of ice
How long will it take to heat 3kg of water from 28oC to 88oC in an electric kettle taking 6a from a 220V supply? [specific heat capacity of water = 4180 J kg-1K-1]
- A. 120s
- B. 570s
- C. 600s
- D. 836s
The silvered surface in a vacuum flask reduces heat loos due to
- A. conduction
- B. convection
- C. radiation
- D. evaporation
The sagging of overhead electrical cables is the consequence of
- A. linear expansivity
- B. superficial expansivity
- C. cubic expansivity
- D. conductivity
A block and tackle system has six pulleys. a force of 50N applied to it lifts a load of weight W. If the efficiency of the system is 40%, calculate W
- A. 300N
- B. 200N
- C. 140N
- D. 120N
The velocity ratio of an inclined plane, inclines at an angle \(\theta\) to the horizontal can be expressed as
- A. (sin \(\theta)^{-1}\)
- B. \(\sin \theta\)
- C. (cos \(\theta)^{-1}\)
- D. \(\cos \theta\)
The engine of a train produces a force of 3000N when moving at 30.ms-1. calculate the power of the engine
- A. 1.00 x 102W
- B. 3.00 x 104W
- C. 9.00 x 104W
- D. 3.00 x 105W
The potential energy in an elastic string of force constant K which has been extended by X metres is expresses as
- A. \(\frac{1}{2}k \Box ^2\)
- B. \(k \Box ^2\)
- C. \(\frac{1}{2}k \Box \)
- D. \(k \Box \)
Which of the following statements about the mouth piece of a telephone is correct? It converts sound energy into
- A. acoustic energy
- B. mechanival energy
- C. electrical energy
- D. heat energy
A stone of mass 2.0kg is thrown vertically upward with a velocity of 20.0 ms-1, calculate the initial kinetic energy of the stone
- A. 200J
- B. 400J
- C. 800J
- D. 1600J
Which of the following source of energy is renewable?
- A. petroleum
- B. charcoal
- C. hydro
- D. nuclear
A force acting on a body causes a change in the momentum of a body from 12 kg ms-1 to 16kg ms-1 in 0.25. Calculate the magnitude of the impulse
- A. 28.0Ns
- B. 20.0Ns
- C. 4.0Ns
- D. 0.8Ns
which of the following statements about simple harmonic motion is correct? The
- A. total mechanical energy is always conserved
- B. linear acceleration is directed to any variable point
- C. linear acceleration varies inversely with displacement
- D. period of oscillation varies linearly as acceleration due to gravity
Which of the following quantities is a vector?
- A. speed
- B. distance
- C. energy
- D. momentum
A car accelerates uniformly from rest at 5 ms-2. Determine its speed after 10s
- A. 50.0ms-1
- B. 25.0ms-1
- C. 2.0ms-1
- D. 0.5ms-1
Uniform speed occurs when there is equal change of
- A. distance in equal times
- B. displacement in equal times
- C. velocity in equal times
- D. acceleration in equal times
A moving car of mass 800 kg experiences a frictional force of 200N. If it accelerates 2 ms-2, calculate the magnitude of the force applied to the car
- A. 600N
- B. 1000N
- C. 1600N
- D. 1800N
A body is rotating in a horizontal circle of radius 2.5m with an angular speed of 5 rad s-1. Calculate the magnitude of the radial acceleration of the body
- A. 62.50ms-2
- B. 31.25ms-2
- C. 12.50ms-2
- D. 10.00ms-2