Compared to an ideal projectile motion under gravity, which of the following is incorrect regarding another projectile motion in which air friction is also considered?

1.	The time of flight decreases.
2.	Decrease in the horizontal component of velocity continuously.
3.	The angle with horizontal is less at the time of striking the ground compared to the angle of projection with horizontal.
4.	The angle with the vertical is less at the time of striking the ground with respect to the angle of projection with vertical.

Two balls are projected to acquire same range with the same initial speed u but at different angles of projection. If maximum height acquired by balls are ${\mathrm{H}}_1 \mathrm{and} {\mathrm{H}}_2$, then (${\mathrm{H}}_1 + {\mathrm{H}}_2$) is: (angle of projection of one projectile is $\mathrm{\theta }$)

(1) ${\tan }^2 \theta$

(2) ${\cot }^2 \mathrm{\theta }$

(3) $\frac{{\mathrm{u}}^2}{2\mathrm{g}}$

(4) tan $\mathrm{\theta }$

At the highest point of trajectory in the ground to the ground projectile, the angle between gravitational acceleration and momentum is

(1) 30°

(2) 45°

(3) 90°

(4) Data insufficient

A particle revolves in a horizontal circle with decreasing velocity. The angle between instantaneous velocity and instantaneous acceleration of the particle at an instant is

(1) < 90°

(2) > 90°

(3) = 90°

(4) $\ge$ 90°

Two projectiles are thrown horizontally from a high cliff in the opposite direction with the same speed 20 m/ s simultaneously. At what time velocities of both particles become perpendicular?

(1) 2$\sqrt{2}$ s

(2) 2 s

(3) 4 s

(4) 4$\sqrt{2}$ s

The equation of the trajectory of a projectile is given as $\mathrm{y} = 4\mathrm{x} - \frac{1}{4}{\mathrm{x}}^2$. The range of the projectile is:

(1) 1 m

(2) 32 m

(3) 16 m

(4) 48 m

A cannon can give a maximum speed of 70 m/s to bombs. The maximum distance up to which cannon projects a bomb is (g = 10 m/${\mathrm{s}}^2$)

(1) 490 m

(2) 245 m

(3) 100 m

(4) 300 m

A man is running horizontally at a velocity of 6 m/s while rain is falling vertically at 6 m/s. The rain strikes the man with a speed of

(1) 6$\sqrt{2}$ m/s

(2) 3$\sqrt{3}$ m/s

(3) 6 m/s

(4) 18 m/s

A man wants to cross a river 600 m wide flowing at 8 m/s in the shortest time. Man has a speed of 6 m/ s in still water. What is the path length covered by the man in the river?

1. Infinite

2. 1 km

3. 100 m

4. 1000 cm