$A$ car accelerates on a horizontal road due to the forces exerted by

$A$ ball of mass $m$ is released from the top of a smooth movable wedge of mass $m$. When the ball collides with the floor,the velocity of the wedge is $v$. Then the maximum height attained by the ball after an elastic collision with the floor is: (Neglect any edge at the lower end of the wedge).

The driver of a car travelling at velocity $v$ suddenly sees a broad wall in front of him at a distance $d$. He should

$A$ force of $5\,N$ acts on a body of mass $5\,kg$ for $1\,s$ and gives it a momentum $p$ and kinetic energy $E$. If the same force accelerates the same body through $1\,m$,the momentum and energy attained by the body are $p'$ and $E'$ respectively. Which of the following relations is correct?

$A$ bullet of mass $0.1\,kg$ moving horizontally with speed $400\,m/s$ hits a wooden block of mass $3.9\,kg$ kept on a horizontal rough surface. The bullet gets embedded into the block and moves $20\,m$ before coming to rest. The coefficient of friction between the block and the surface is $........$ (Given $g=10\,m/s^2$)

Consider the following statements $A$ and $B$ and identify the correct answer:
$A$. When a person walks on a rough surface,the direction of the frictional force exerted by the surface on the person is in the same direction as his motion.
$B$. When a cycle is in motion,the force of friction exerted by the ground on the front wheel is in the backward direction.