Two balls of masses 3 kg and 6 kg are moving with velocities of 4 m/sec and 1 m/sec respectively, towards each other along the line of their centers. After impact the 3 kg ball comes to rest. This can happen only if the coefficient of restitution between the balls is
2/3
1/5
3/5
1/3
Correct Answer :
B. 1/5
Related Questions
Power developed by a torque, is
2πNT kg m/min
2πNT/4500 h.p
2πNT /60 watts
All the above
A projectile has maximum range of 40 m on a horizontal plane. If angle of projection is a and the time of flight is 1 second, then sin a must be about (Assume g = 10 m/sec²)
1/4
1/3
1/2
1/5
A ladder of weight 'w' rests against a smooth vertical wall, and rests on rough horizontal ground, the coefficient of friction between the ladder and the ground being 1/4. The maximum angle of inclination of the ladder to the vertical, if a man of weight 'w' is to walk to the top of it safely, is tan'1 x, where x is
1/4
1/3
3
4
In case of S.H.M. the period of oscillation (T), is given by
T = 2ω/π²
T = 2π/ω
T = 2/ω
T = π/2ω
Two shots fired simultaneously from the top and bottom of a vertical tower with elevations of 30° and 45° respectively strike a target simultaneously. If horizontal distance of the target from the tower is 1000 m, the height of the tower is
350 m
375 m
400 m
425 m
Impulse can be obtained from a
Force-displacement diagram
Force-time diagram
Velocity-time diagram
Velocity-displacement diagram
The following statement is one of the laws of Dynamic friction
The force of friction always acts in a direction opposite to that in which a body is moving
The magnitude of the kinetic friction bears a constant ratio to the normal reaction between two surfaces. The ratio being slightly less than that in the case of limiting friction
For moderate speeds the force of friction remains constant but decreases slightly with the increase of speed
All the above
A point subjected to a number of forces will be in equilibrium, if
Sum of resolved parts in any two directions at right angles, are both zero
Algebraic sum of the forces is zero
Two resolved parts in any two directions at right angles are equal
Algebraic sum of the moments of the forces about the point is zero
A particle of mass 2 kg executes simple harmonic motion of frequency 6/71 Hz and amplitude 0.25 m. Its maximum kinetic energy is
4.5 J
9.0 J
12.0 J
18.0 J
The ratio of the ranges on the inclined plane with motion upward and with motion downward for a given velocity, angle of projection will be
sin (α + β)/sin (α - β)
sin (α - β)/sin (α + β)
cos (α - β)/cos (α + β)
tan (α - β)/tan (α + β)
Angular acceleration of a particle may be expressed as
Radians/sec2
Degrees/sec2
Revolutions/sec
All the above
A sphere is resting on two planes BA and BC which are inclined at 45° and 60° respectively with the horizontal. The reaction on the plane BA will be
Less than that on BC
More than that of BC
Equal to that on BC
None of these
The displacement of a particle which moves along a straight line is given by S = 4t3 + 3t2- 10 where S is in meters and t is in seconds. The time taken by the particle to acquire a velocity of 18 m/sec from rest, is
½ sec
1 sec
1.2 sec
1.5 sec
A projectile is fired at an angle θ to the vertical. Its horizontal range will be maximum when θ is
0°
30°
45°
90°
Parallelogram Law of Forces states, if two forces acting simultaneously on a particle be represented in magnitude and direction by two adjacent sides of a parallelogram, their resultant may be represented in magnitude and direction by
Its longer side
Its shorter side
The diagonal of the parallelogram which does not pass through the point of intersection of the forces
The diagonal of the parallelogram which passes through the point of intersection of the forces
A body of weight w placed on an inclined plane is acted upon by a force P parallel to the plane which causes the body just to move up the plane. If the angle of inclination of the plane is θ and angle of friction is φ, the minimum value of P, is
w sin (φ - θ)/cos φ
w sin (θ - φ)/cos φ
w cos (θ + φ)/cos φ
w sinθ cos(θ - φ)/sin φ
A retarding force on a body does not
Change the motion of the body
Retard the motion of the body
Introduce the motion of the body
None of these
A load of 500 kg was lifted through a distance of 13 cm. by an effort of 25 kg which moved through a distance of 650 cm. The efficiency of the lifting machine is
50 %
40 %
55 %
30 %
The C.G. of the shaded area of the below figure from the x-axis is 
a/4
3a/4
3b/10
3a/10
The resultant of two forces P and Q acting at an angle θ, is
P2 + Q2 + 2P sin θ
P2 + Q2 + 2PQ cos θ
P2 + Q2 + 2PQ tan θ
√(P2 + Q2 + 2PQ cos θ)
A particle is dropped from the top of a tower 60 m high and another is projected upwards from the foot of the tower to meet the first particle at a height of 15.9 m. The velocity of projection of the second particle is
16 m/sec
18 m/sec
20 m/sec
22 m/sec
The practical units of work, is
Erg
Joule
Newton
Dyne
Minimum pull in a suspended cable with supports at two ends is equal to
Horizontal thrust
Support reactions
Resultant of horizontal thrust and support reaction
Half the weight of the cable
Power can be expressed as
Work/energy
Work/time
Work × time
Work/distance
The centre of gravity of a quadrant of a circle lies along its central radius at a distance of
0.2 R
0.4 R
0.3 R
0.6 R
It is observed that in a certain sinusoidal oscillation, the amplitude is linearly dependent on the frequency f. If the maximum velocity during the oscillation is V, then V must be proportional to
f
1/f
1/f²
f²
Which one of the following laws is not applicable to a simple pendulum?
The time period does not depend on its magnitude
The time period is proportional to its length l
The time period is proportional to l, where l is length
The time period is inversely proportional to g, where g is the acceleration due to gravity
For a non-concurrent force system to be in equilibrium
Only the closure of force polygon is sufficient
Only the closure of funicular polygon is sufficient
Both force polygon and funicular polygon must close
None of the above
A rod AB carries three loads of 30 N, 70 N and 100 N at distances of 20 mm, 90 mm and 150 mm respectively from A. Neglecting the weight of the rod, the point at which the rod will balance is
109.5 mm from A
119.5 mm from A
125.5 mm from A
132.5 mm from A
If the velocity of projection is 4 m/sec and the angle of projection is α°, the maximum height of the projectile from a horizontal plane, is
u² cos² α/2g
u² sin² α/2g
u² tan² α/2g
u² sin 2α/2g