A gun applied a force $F$ on a bullet which is given by $$F=\left(100-0.5 \times 10^5 t\right) \mathrm{N}$$. The bullet emerges out with speed $$400 \mathrm{~m} / \mathrm{s}$$. Then find out the impulse exerted till force on the bullet becomes zero.

Assertion : A glass ball is dropped on concrete floor can easily get broken compared if it is dropped on wooden floor.

Reason : On concrete floor glass ball will take less time to come to rest.

A wooden wedge of mass $$M$$ and inclination angle $$(\alpha)$$ rest on a smooth floor. A block of mass $m$ is kept on wedge. A force $$F$$ is applied on the wedge as shown in the figure such that block remains stationary with respect to wedge. So, magnitude of force $$F$$ is

A piece of ice slides down a rough inclined plane at $$45^{\circ}$$ inclination in twice the time that it takes to slide down an identical but frictionless inclined plane. What is the coefficient of friction between ice and incline?