A bus driving along at 39.6 kmph is approaching a person who is standing at the bus stop, while honking
repeatedly at an interval of 30 seconds. If the speed of the sound is 330 m/s, at what interval will the person
hear the horn ?
(A) 31 seconds
(B) 29 seconds
(C) 30 seconds
(D) the interval will depend on the distance of the bus from the passenger
A book is resting on shelf that is undergoing vertical simple harmonic oscillations with an amplitude of
2.5 cm. What is the minimum frequency of oscillation of the shell for which the book will lose contact with
the shelf ? (Assume that g = 10 m/s2)
(A) 20 Hz (B) 3.18 Hz (C) 125.6 Hz (D) 10 Hz
A nucleus has a half-life of 30 minutes. At 3 PM its decay rate was measured as 120,000 counts/sec. What
will be the decay rate at 5 PM ?
(A) 120,000 counts/sec (B) 60,000 counts/sec
(C) 30,000 counts/sec (D) 7,500 counts/sec
A point source of light is placed at the bottom of a vessel which is filled with water of refractive index μ to a
height h. If a floating opaque disc has to be placed exactly above it so that the source is invisible from above,
the radius of the disc should be-
A charge +q is placed somewhere inside the cavity of a thick conducting spherical shell of inner radius R1
and outer radius R2. A charge – Q is placed at a distance r > R2 from the centre of the shell. Then the electric
field in the hollow cavity-
(A) depends on both +q and – Q (B) is zero
(C) is only that due to – Q (D) is only that due to +q
A comet (assumed to be in an elliptical orbit around the sun) is at a distance of 0.4 AU from the sun at the
perihelion. If the time period of the comet is 125 years, what is the aphelion distance ? AU : Astronomical
Unit.
(A) 50 AU (B) 25 AU (C) 49.6 AU (D) 24.6 AU
A bead of mass m is attached to the mid-point of a taut, weightless string of length l and placed on a
frictionless horizontal table Under a small transverse displacement x, as shown, if the tension in the string is T, then the frequency of
oscillation is-
Two masses m1 and m2 connected by a spring of spring constant k rest on a frictionless surface. If the
masses are pulled apart and let go, the time period of oscillation is
Pure mathematics is the world's best game. It is more absorbing than chess, more of a gamble than poker, and lasts longer than Monopoly. It's free. It can be played anywhere - Archimedes did it in a bathtub.
Richard J. Trudeau, Dots and Lines
2 is not equal to 3 – not even for very large values of 2.