National University of Sciences and technology NUST is very well known engineering university of Pakistan. NUST offers a wide range of programs to their students in many different fields. Their main motive is to provide quality education to their students, because of that their fee is also high as compared to other universities but they also provide need based scholarships to their students. NUST NET entry test is considered to be one of the toughest test of Pakistan, students have to give their 100% in order to secure their admission. NUST NET admissions are open till 15th December 2018 and entry test will start from 28th December 2018.
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Waves and Oscillations
Waves in which the displacement of the medium is in the same direction as, or the opposite direction to, the direction of travel of the wave are called?
- Traverse waves
- Electromagnetic waves
- Compression waves
- None of the above
Longitudinal waves, also known as “l-waves”, are waves in which the displacement of the medium is in the same direction as, or the opposite direction to, the direction of travel of the wave. Mechanical longitudinal waves are also called compressional waves or compression waves, because they produce compression and rarefaction when travelling through medium. The other main type of wave is the transverse wave, in which the displacements of the medium are at right angles to the direction of propagation.
For a liquid flowing in a pipe in horizontal direction, which of the following must remain constant?
- Pressure energy
- Kinetic energy per unit volume
- Potential energy per unit volume
- As per Bernoulli’s theorem all of them would change
Potential energy per unit volume
Bernoulli’s equation has three elements. (1) Pressure energy = P; (2) Kinetic energy per unit volume = 1/2pv2 and (3) Potential energy per unit volume = pgh. For horizontal pipe ‘h’ is same so (3) would remain constant. (1) and (2) may change dependent on the cross sectional area of pipe across the horizontal length.
Motion, Force, Work & Energy
A tubewell pumps out 2400 kg of water per minute. Water is coming out with a velocity of 3m s-_1. What is the power of pump?
- 980 W
- 180 W
- 900 W
- 120 W
Mass of water pumped per second = 2400 / 60 = 40 kg
v=3m s_1, k.E=1/2 (40) (3)2 = 180 JS -_1 Power = 180 J S_1 = 180 watt