The following are correct about the human eye and camera except that they

The distance covered by the object is $\boxed{\text{E. } 9000.0 \text{ m}}$.

39. A car moving at $10 \text{ ms}^{-1}$ decelerates at $5 \text{ ms}^{-2}$ for $1.34 \text{ s}$. Calculate the magnitude of its final velocity.

Initial velocity, $u = 10 \text{ ms}^{-1}$
Acceleration (deceleration), $a = -5 \text{ ms}^{-2}$
Time, $t = 1.34 \text{ s}$

The magnitude of its final velocity is $\boxed{\text{A. } 3.3 \text{ ms}^{-1}}$.

40. A uniform rod AB of mass $20 \text{ kg}$ is pivoted at A. The rod is kept in equilibrium by a rope of tension $1000 \text{ N}$ making an angle of $30^\circ$ to the rod. If the rope is attached to the rod at a distance of $2 \text{ m}$ from the pivot, calculate the length of the rod. [$g = 10 \text{ ms}^{-2}$]

For a uniform rod, its weight acts at its center of mass, which is at $L/2$ from the pivot.

This is a clockwise moment.

This is an anticlockwise moment. The perpendicular component of the tension is $T \sin \theta$.

The length of the rod is $\boxed{\text{E. } 10.0 \text{ m}}$.

41. A ball of mass $5 \text{ kg}$ falls from a height of $120 \text{ m}$. If its potential energy after falling through a distance $x$ is $3.5 \text{ kJ}$, neglecting air resistance, calculate $x$. [$g = 10 \text{ ms}^{-2}$]

The initial height is $H = 120 \text{ m}$.
The height after falling $x$ is $h_f = H - x = (120 - x) \text{ m}$.

The distance $x$ is $\boxed{\text{C. } 50 \text{ m}}$.

42. A machine with a velocity ratio of 5 was used to move a load of $2000 \text{ N}$ with an effort of $500 \text{ N}$. Calculate the efficiency of the machine.

The efficiency of the machine is $\boxed{\text{E. } 80\%}$.

43. A body $x$ of mass $2 \text{ kg}$ moving with a velocity of $20 \text{ ms}^{-1}$ collides with another body $y$ of mass $3 \text{ kg}$ moving in the opposite direction. If the bodies stick together and move in the direction of $x$ at a velocity of $6 \text{ ms}^{-1}$, calculate the velocity of $y$.

Mass of body x, $m_x = 2 \text{ kg}$
Initial velocity of body x, $u_x = 20 \text{ ms}^{-1}$
Mass of body y, $m_y = 3 \text{ kg}$
Initial velocity of body y, $u_y = ?$ (since it's in the opposite direction, it will have a negative sign)
Final velocity of combined bodies, $v = 6 \text{ ms}^{-1}$ (in the direction of x)
According to the conservation of momentum:

The magnitude of the velocity of y is $3.3 \text{ ms}^{-1}$. The negative sign indicates it was moving in the opposite direction to body x.
The velocity of y is $\boxed{\text{E. } 3.3 \text{ ms}^{-1}}$.

44. A metal rod of length $2.01 \text{ m}$ at $20^\circ\text{C}$ was heated to $30^\circ\text{C}$. Calculate the new length of the rod. [$\alpha = 1.7 \times 10^{-5} \text{ K}^{-1}$]

Since a change of $1^\circ\text{C}$ is equal to a change of $1 \text{ K}$, $\Delta T = 10 \text{ K}$.

Rounding to four decimal places, $L_f \approx 2.0103 \text{ m}$.
The new length of the rod is $\boxed{\text{C. } 2.0103 \text{ m}}$.