A ball of mass 0.5 kg moving horizontally at $$10 \mathrm{~ms}^{-1}$$ strikes a vertical wall and rebounds with speed $$v$$. The magnitude of the change in linear momentum is found to be $$8.0 \mathrm{~kg}-\mathrm{~ms}^{-1}$$. The magnitude of $$v$$ is
A mass of 1 kg falls from a height of 1 m and lands on a massless platform supported by a spring having spring constant $$15 \mathrm{~Nm}^{-1}$$ as shown in the figure. The maximum compression of the spring is (acceleration due to gravity $$=10 \mathrm{~ms}^{-2}$$)
A bead of mass 400 g is moving along a straight line under a force that delivers a constant power 1.2 W to the bead. If the bead is initially at rest, the speed it attains after 6 s in $$\mathrm{ms}^{-1}$$
Masses $$m\left(\frac{1}{3}\right)^N \frac{1}{N}$$ are placed at $$x=N$$, when $$N=2,3,4 \ldots \infty$$. If the total mass of the system is $$M$$, then the centre of mass is