Mechanics | Relativity Answers

A 2.0 kg stone tied to the the end of an inextensible string is whirled around in a horizontal circle of radius 1.5 m at auniform angular speed
2π
rad/s Calculate the rotational kinetic energy of the stone.

220.7 J

88.8 J

47.4 J

246.7 J

A satellite orbits the earth at an altitude of 600 km with an orbital speed of 27 000km/hr. What is its period of revlution. Take the radius of the earth as 6400 km.

97.7 min

36.4 min

120.3 min

73.7 min

Which of the following is INCORRECT?
a. The coefficient of static friction depends on the nature of the surfaces in contact
b. static friction is larger than kinetic friction for any given surfaces in contact
c. The coefficient of friction is independent of the relative velocity of the surfaces in contact
d. The coefficient of friction is dependent on the area of the surfaces in contact.

A pulley is rotating at the rate of 32 rev/min. A motor speeds up the wheel so that 30 s later it is turning at 82 rev/min. what is the average angular acceleration in radians per second
a. 0.17
b. 2.11
c. 0.32
d. 1.41

A system of two point masses connected by a rigid massless rod and set into rotation about an axis through throd joining the particles is called ---------
a. couple
b. dumbbell
c. gyroscope
d. torque

A system of four particles made of 20 g at (4,0), 30 g at (0,6), 25 g at (-4,3) and 40 g at (-3,2) in the xy-plane, rotate about the z-axis through the centre of the coordinate system. The coordinates are given in units of centimetres. Calculate the moment of inertia of the system.

a. 2545gcm2
b. 1850gcm2
c. 3234gcm2
d. 2545gcm2

The tendency of an object rotating about an axis to resist any of its roational motion is refered to as ------
angular momentum
gyration
moment of inertia
torque

The motion of a rigid object for which all its constituent particles undergo the same kind of diplacement is refered to as -------- motion
oscillatory
translational
random
rotational

A froced oscillation for which the frequency of the external periodic impulse that drives it is equal to the natural frequency of the oscillation is refered to as
resonance
damped oscillation
coupled oscillation
quality factor

A particle executing simple harmonic motion has velocities
4cms(−1)
at
6cm
and
6cm−1
at
4cm
respectively from the equilibrium position.Determine the amplitude of oscillation