How to calculate percentage? Give example.
Answer: In mathematics, a percentage is a number or ratio that can be expressed as a fraction of 100. If... View Article
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If a,b,c,d are four positive real numbers such that abcd = 1, then the minimum value of (1 + a)(1 + b)(1 + c)(1 + d) is equal to_________?
Answer: 16 Real numbers are numbers that include both rational and irrational numbers. Rational numbers such as integers (-2, 0,... View Article
A student wants to project the image of a candle flame on the walls of school laboratory by using a lens (1) Which type of lens should be use? (2) At what distance in terms of focal length F of the lens should be place the candle flame so as to get (a) a magnified, and (b) a diminished imaged respectively on the wall?
Answer: (1) The student should use a convex lens since it will allow him to project an image on the... View Article
Following cards are put facing down: A E I O U What is the chance of drawing out (1) A card marked U? (2) A vowel (3) A or I (4) A consonant?
Answer: Probability is a measure of the likelihood of an event to occur. Many events cannot be predicted with total... View Article
The height of a cone is 15 cm and its volume is 1570 cm3. Find the radius of the base. (Use π = 3.14)
Answer: A cone is a shape formed by using a set of line segments or the lines which connects a... View Article
If force F, work W and velocity v are taken as fundamental quantities. What is the dimensional formula of time?
Answer: Velocity Velocity is defined as the rate of change of the object’s position with respect to a frame of... View Article
If force F, time t and velocity V are taken as fundamental quantities and K is the dimensionless constant of proportionality. What is the dimensional formula for mass?
Answer: Velocity Velocity is defined as the rate of change of the object’s position with respect to a frame of... View Article
The difference between a 2-digit number and the number obtained by interchanging the digits is 36. What is the difference between the sum and the difference of the digits of the number if the ratio between the digits of the number is 1:2 ? (1) 4 (2) 8 (3) 16 (4) None of these
The difference between a 2-digit number and the number obtained by interchanging the digits is 36. What is the difference... View Article
The position of a body moving along x-axis at time t is given by x = (t2– 4t + 6)m. The distance travelled by body in time interval t = 0 to t = 3s is (1) 5m (2) 7m (3) 4m (4) 3m
Answer: (1) 5m x = t2 – 4t + 6 The change in velocity is expressed as \(\begin{array}{l}\frac{dx}{dt}= 2t –... View Article
A jet airplane travelling at the speed of 500 kmh-1 ejects its products of combustion at the speed of 1500 kmh-1 relative to the jet plane. What is the speed of the latter with respect to an observer on ground? (1) 500 km h-1 (2) -1000 km h−1 (3) 1500 kmh-1 (4) 2000 kmh-1
Answer: – 1000kmh-1 Relative velocity is defined as the velocity of an object B in the rest frame of another... View Article
A particle of mass m is moving in a circular path of constant radius r such that centripetal acceleration is varying with time t as k2rt2, where k is a constant. The power delivered to the particle by the force acting on it is (1) m2k2r2t2 (2) mk2r2t (3) mk2rt2 (4) mkr2t
Answer: Centripetal acceleration is defined as the property of the motion of an object, traversing a circular path. Any object... View Article
The distance x covered by a particle in one-dimensional motion varies with time t as x2 = at2 + 2bt + c. The acceleration of the particle varies as (1) x−3 (2) x3/2 (3) x2 (4) x-2/3
Answer: x-3 Let v be velocity,α be the acceleration then, x2 = at2 + 2bt + c 2xv = 2at... View Article
A pump motor is used to deliver water at a certain rate from a given pipe. To obtain thrice as much water from the same pipe at the same time, the power of the motor has to be increased to (1) 2 times (2) 9 times (3) 27 times (4) 81 times
Answer:(3) 27 times Power is defined as the rate of doing work, it is the work done in unit time.... View Article
A charge particle (charge q) is moving in a circle of radius R with uniform speed. v The associated magnetic moment m is given by_______
Answer: A charge particle (charge q) is moving in a circle of radius R with uniform speed. v The associated... View Article
For a plane convex lens (μ=1.5) having radius of curvature 10cm. It is silvered on its plane surface. Find focal length after silvering (1) 10cm (2) 20cm (3) 15cm (4) 25cm
Answer: (1) 10cm An optical lens is generally made up of two spherical surfaces. If those surfaces are bent outwards,... View Article
Calculate the ratio of 4th Bohr’s to 2nd Bohr’s orbit of He+ ion.
Answer: The Bohr model suggests that the electrons in atoms are in various energy orbits around the nucleus. In defining... View Article
A ball initially at rest and it is dropped from building of height 10 m to ground. If the coefficient of restitution is e = 0.7. After collision, the ball rebounds back up to height h, find the value of h. (g = 9.8 m/s2)
Answer: A ball initially at rest and it is dropped from building of height 10 m to ground. If the... View Article
A body starts from rest with uniform acceleration. The velocity of the body after t seconds is v. The displacement of the body in last three seconds is (1) 3v/2[(t – 3)] (2) 3v/2[(t + 3)] (3) 3v[1 – 3/2t] (4) 3v[1 + 3/2t]
Answer: (3) 3v[1 – 3/2t] Let a be the uniform acceleration of the body . Then v = at a... View Article
A ring of radius 1 m is lying on the surface of liquid. It is lifted from the liquid surface by a force of 4 newtons in such a way that the liquid film in it remains intact. What is the surface tension of liquid?
Answer: Surface tension is the tension of the surface film of a liquid caused by the attraction of the particles... View Article
The potential difference V and the current I flowing through an instrument in an AC circuit are given by V = 5cosωt volt, I = 2sinωt Amp . The power dissipated in the circuit is (1) 5 watt (2) 10 watt (3) 2.5 watt (4) 0
Answer: (4) 0 In an AC circuit, the power dissipated in the circuit is given as follows P = Vrms... View Article
