Question 1:
moderateConsider 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:Â
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
Question 2:
easyA passenger in the bus finds that his suit-case suddenly starts sliding backwards. This means that the bus is :
This is due to inertia of motion.Â
Question 3:
easyPassengers standing in a bus are thrown outwards when the bus takes a sudden turn. This happens because of :
Due to inertia of direction person inside the bus has a tendency to move in a straight line. In case of sudden turn body ties to maintain its linear motion.
Question 4:
moderateWhich 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.
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
Question 5:
moderateAn object experiences no acceleration which of the following can NOT be true for the objectÂ
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
Question 6:
easyGenerally it is said “Normal reaction always acts perpendicular to the surface of contact” :
Normal reaction force is always normal ( Perpendicular ) to the surface. Â
Question 7:
easyIn 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 :
Due to inertia of rest clark want to remain at rest.Â
Question 8:
moderateA \(3.0\text{ kg}\) 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 \(t = 2\text{ sec}\).
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 \(F = ma = 3.0 \times 60 = 180\text{ N}\).
Question 9:
easyA large force \(f\) acts on a particle of mass \(m\) for a short time \(t\). The impulse imparted to the particle is given by
Impulse is defined as the product of the average force and the short time interval over which it acts, i.e., \(\text{Impulse} = f \times t\).
Question 10:
easyA 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
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 \(Delta p = m(v - (-u)) = 2mu = 2 \times 0.15 \times 14.14 \approx 4.24\text{ kg m/s}\).