## Question

### Solution

Correct option is

48.23

(a) For hitting the ship the range of cannon must be equal to the distance of ship from cannon, i.e.,

i.e., to hit the ship the cannon must be elevated at an angle of

(b) As  depending on θ there are two times of flight.

(c) The maximum range of cannon (when θ = 45°).

And as initially the ship is  so to become out of maximum range of cannon, the ship should be moved away from the harbour from its initial position by at least

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Particles P and Q of mass 20 g and 40g respectively are simultaneously projected from points A and B on the ground. The initial velocities of Pand Q make 45° and 135° angles respectively with the horizontal AB as shown in the figure. Each particle has an initial speed of 49 m/s. The separation AB is 245 m. Both particles travel in the same vertical and plane and undergo a collision. After collision P retraces its path. Determine the position of Q when it hits the ground. How much time after the collision does the particle Q take to reach the ground? (Take g = 9.8 m/s2)