A uniform chain of length \(L\) and mass \(M\) is lying on a smooth table and one-third of its length is hanging vertically down over the edge of the table. If \(g\) is acceleration due to gravity, the work required to pull the hanging part on the table is:

1. \(MgL\)

2. \(MgL/3\)

3. \(MgL/9\)

4. \(MgL/18\)

If W₁, W₂ and W₃ represent the work done in moving a particle from A to B along three different paths 1, 2 and 3 respectively (as shown) in the gravitational field of a point mass m, find the correct relation between W₁, W₂ and W₃ 

(1) W₁ > W₂ > W₃

(2) W₁ = W₂ = W₃

(3) W₁ < W₂ < W₃

(4) W₂ > W₁ > W₃

The displacement x of a particle moving in one dimension under the action of a constant force is related to the time t by the equation $t=\sqrt{x}+3$, where x is in meters and t is in seconds. The work done by the force in the first 6 seconds is 

(1) 9 J

(2) 6 J

(3) 0 J

(4) 3 J

A force \(F = -k(y\hat i +x\hat j)\) (where \(k\) is a positive constant) acts on a particle moving in the \(xy\text-\)plane. Starting from the origin, the particle is taken along the positive \(x\text-\)axis to the point \((a,0)\) and then parallel to the \(y\text-\)axis to the point \((a,a)\). The total work done by the force on the particle is:
1. \(-2ka^2\)
2. \(2ka^2\)
3. \(-ka^2\)
4. \(ka^2\)

A lorry and a car moving with the same K.E. are brought to rest by applying the same retarding force, then:

1. Lorry will come to rest in a shorter distance

2. Car will come to rest in a shorter distance

3. Both will come to rest in a same distance

4. None of the above

A particle free to move along the x-axis has potential energy given by $U\left(x\right)=k[1-e^{-x^2}]$ for $-\infty \le x\le +\infty$, where k is a positive constant of appropriate dimensions. Then 

(1) At point away from the origin, the particle is in unstable equilibrium

(2) For any finite non-zero value of x, there is a force directed away from the origin

(3) If its total mechanical energy is k/2, it has its minimum kinetic energy at the origin

(4) For small displacements from x = 0, the motion is simple harmonic

The kinetic energy acquired by a mass m in travelling a certain distance d starting from rest under the action of a constant force is directly proportional to 

(1) $\sqrt{m}$

(2) Independent of m

(3) $1/\sqrt{m}$

(4) m

An open knife edge of mass 'm' is dropped from a height 'h' on a wooden floor. If the blade penetrates upto the depth 'd' into the wood, the average resistance offered by the wood to the knife edge is 

(1) mg

(2) $mg\left(1-\frac{{\displaystyle h}}{{\displaystyle d}}\right)$

(3) $mg\left(1+\frac{{\displaystyle h}}{{\displaystyle d}}\right)$

(4) $mg{\left(1+\frac{{\displaystyle h}}{{\displaystyle d}}\right)}^2$

A body is moving along a straight line by a machine delivering constant power. The distance moved by the body in time t is proportional to 

(1) t^1/2

(2) t^3/4

(3) t^3/2

(4) t²

Two particles of masses m₁ and m₂ in projectile motion have velocities ${\overrightarrow{v}}_1$ and ${\overrightarrow{v}}_2$ respectively at time t = 0. They collide at time t₀. Their velocities become ${\overrightarrow{v}}_1\text{'}$ and ${\overrightarrow{v}}_2\text{'}$ at time 2t₀ while still moving in air. The value of $\left|(m_1\overrightarrow{v_1}\text{'}+m_2\overrightarrow{v_2}\text{'})-(m_1\overrightarrow{v_1}+m_2\overrightarrow{v_2})\right|$ is 

1. Zero

2. $(m_1+m_2)g{t}_0$

3. $2(m_1+m_2)g{t}_0$

4. $\frac{1}{2}(m_1+m_2)g{t}_0$