A body of mass 1 kg begins to move under the action of a time dependent force \(F = 2 t\) \(\hat{i} + 3 t^{2}\ \hat{j}\) N, where \(\hat{i}\) and \(\hat{j}\) are unit vectors along X and Y axis, What power will be developed by the force at the time (t) ?
1. \(\left(2 t^{2} + 4 t^{4}\right) W\)
2. \(\left(2 t^{3} + 3 t^{4}\right) W\)
3. \(\left(2 t^{3} + 3 t^{5}\right) W\)
4. \(\left(2 t + 3 t^{3}\right) W\)
What is the minimum velocity with which a body of mass m must enter a vertical loop of radius R so that it can complete the loop?
1.
2.
3.
4.
A block of mass \(10\) kg, moving in the \(x\text-\)direction with a constant speed of \(10\) ms-1, is subjected to a retarding force \(F=0.1x\) J/m during its travel from \(x =20\) m to \(30\) m. Its final kinetic energy will be:
1. | \(475\) J | 2. | \(450\) J |
3. | \(275\) J | 4. | \(250\) J |
A particle of mass m is driven by a machine that delivers a constant power of k watts. If the particle starts from rest the force on the particle at time t is:
(1)
(2)
(3)
(4)
Two particles of masses m1,m2 move with initial velocities u1 and u2. On collision, one of the particles get excited to higher level, after absorbing energy . If final velocities of particles be v1 and v2, then we must have
(a)m12u1+m22u2-=m12v1+m22v2
(b)m1u12+m2u2=m1v12+m2v22-
(c)m1u12+m2u22-=m1v12+m2v22
(d)m12u12+m22u22+=m12v12+m22v22
A ball is thrown vertically downwards from a height of \(20\) m with an initial velocity \(v_0\). It collides with the ground, loses \(50\%\) of its energy in a collision and rebounds to the same height. The initial velocity \(v_0\) is: (Take \(g = 10~\text{m/s}^2\))
1. \(14~\text{m/s}\)
2. \(20~\text{m/s}\)
3. \(28~\text{m/s}\)
4. \(10~\text{m/s}\)
Two particles A and B. move with constant velocities v1 and v2. At the initial moment, their position vectors are and respectively. The condition for particles A and B for their collision is-
(1)
(2)
(3)
(4) r1-r2=v1-v2
On a frictionless surface, a block of mass M moving at speed v collides elastically with another block of same mass M which is initially at rest. After collision the first block moves at an angle θ to its initial direction and has a speed v/3. The second block's speed after the collision is:
(1)2√2v/3
(2)3v/4
(3)3v/√2
(4)√3v/2
The force F acting on a particle of mass m is indicated by the force-time graph shown below. The change in momentum of the particle over the time interval from zero to 8 s is:
1. 24 Ns
2. 20 Ns
3. 12 Ns
4. 6 Ns