Consider the following two statements:
(A) Linear momentum of a system of particles is zero
(B) Kinetic energy of a system of particles is zero
Then:
1. A does not imply B and B does not imply A
2. A implies B but B does not imply A
3. A does not imply B but B implies A
4. A implies B and B implies A
View Answer
When kinetic energy of the system is zero, speed of objects will be zero so momentum will always be zero.
Whereas momentum being a vector quantity may be zero when directions of velocities cancel each other. so speed and kinetic energy may of may not be zero when momentum is zero
Which of the following option is correct regarding given statements :-
(I) It is possible for an object to have motion in the absence of forces on the object.
(II) It is possible to have forces on an object in the absence of motion of the object.
1. Only (I) is correct
2. Only (II) is correct
3. Both (I) & (II) are correct
4. neither (I) nor (II) is correct
View Answer
Statement I is correct because in absence of force object can move with constant velocity.
Statement II is correct because if many forces act on an object such that resultant is zero, the object will be in static equilibrium
An object experiences no acceleration which of the following can NOT be true for the object
1. A single force acts on the object
2. No forces act on the object
3. Forces act on the object, but the forces cancel
4. All of the above
View Answer
If only one force acts on the object it will be the net force. So the object will accelerate and it can't be at rest
Generally it is said “Normal reaction always acts perpendicular to the surface of contact” :
1. The statement is always correct
2. The statement is some times correct
3. The statement is correct
4. I can not comment, the way you have designed the question made me speech less.
View Answer
Normal reaction force is always normal ( Perpendicular ) to the surface.
In the motion picture ‘It happened one night’ (columbia pictures, 1934), Clark ceable in
standing inside a stationary bus in front of the claudetle colbert, who is seated, the bus suddenly starts moving forward and clark fall into claudetters lap which of following explains this phenomena best :
1. Newton's first law (Inertia of rest)
2. Newton's second law
3. Newton's third law
4. None of these
View Answer
Due to inertia of rest clark want to remain at rest.
A \(3.0\text{ kg}\) mass is moving in a plane, with its x and y coordinates given by \(x = 24t^2 – 1\) and \(y = 3t^3 + 2\), where x and y are in meters and t is in second. Find the magnitude of the net force acting on this mass at \(t = 2\text{ sec}\).
1. \(120\text{ N}\)
2. \(150\text{ N}\)
3. \(180\text{ N}\)
4. \(210\text{ N}\)
View Answer
Differentiating position equations twice yields accelerations: \(a_x = 48\text{ m/s}^2\) and \(a_y = 18t\text{ m/s}^2\). At \(t = 2\text{ s}\), \(a_y = 36\text{ m/s}^2\). Total acceleration \(a = \sqrt{a_x^2 + a_y^2} = 60\text{ m/s}^2\). The net force is \(F = ma = 3.0 \times 60 = 180\text{ N}\).
A ball of mass \(0.15\text{ kg}\) is dropped from a height \(10\text{ m}\), strikes the ground and rebounds to the same height. The magnitude of impulse imparted to the ball is (\(g = 10\text{ m/s}^2\)) nearly
1. 1.4 kg m/s
2. 0 kg m/s
3. 4.2 kg m/s
4. 2.1 kg m/s
View Answer
The velocity of the ball just before striking the ground is \(u = \sqrt{2gh} = \sqrt{2 \times 10 \times 10} = 14.14\text{ m/s}\). Since it rebounds to the same height, its velocity just after is \(v = 14.14\text{ m/s}\) upwards. The change in momentum is \(Delta p = m(v - (-u)) = 2mu = 2 \times 0.15 \times 14.14 \approx 4.24\text{ kg m/s}\).