Home
Class 11
PHYSICS
A fighter plane is flying horizontally a...

A fighter plane is flying horizontally at a height of `250m` from ground with constant velocity of `500m//s`. It passes exactly over a cannon which can fire a shell at any time in any direction with a speed of `100m//s`. Find the duration of time for which the plane is in danger of being hit by a cannon shell.

Text Solution

Verified by Experts

We first find the area in which the cannon shell can reach. The equation of trajectory for cannon shell is
`y=x tantheta-((1)/(2)gx^(2))/(u^(2))sec^(2)theta`.......(`1`)
For maximum `y` for a given value of `x`-
`(dy)/(d(tantheta))=x-((1)/(2)gx^(2))/(u^(2))(2tantheta)=0 rArr tantheta=(u^(2))/(gx)`
Putting in equation (`1`)
`y_(max)=x(u^(2))/(gx)-((1)/(2)gx^(2))/(u^(2))[1+(u^(4))/(g^(2)x^(2))]=(u^(2))/(2g)-((1)/(2)gx^(2))/(u^(2))`
`:. ` The cannon shell can hit an area given by
`y le (u^(2))/(2g)-((1)/(2)gx^(2))/(u^(2))`
Given in the problem `y=250m`, `u=100m//s`, `g=10m//s`.
Putting these value we get,
`(x^(2))/(2000) le 250 rArr -500sqrt(2) le x le 500sqrt(2)`
`:.` Plane is in danger for a period of `(1000sqrt(2))/(500)=2sqrt(2)sec`
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

Similar Questions

Explore conceptually related problems

A fighter plane flying horizontally at an altitude of 2km with speed of 540 kmph passes directly over head an anti aircraft gun.If the gun can fire a bullet at the muzzle speed of 500ms^( - 1) ,at what angle with the vertical the gun should fire the bullet so that the bullet hits the plane?

A ball is thrown horizontally from a height of 20m .If hits the ground with a velocity of 3 times the velocity of projection.The velocity of projection is 3.5x m//s then x is

Knowledge Check

  • A ball is thrown horizontally with a speed of 20 m//s from the top of a tower of height 100m Time taken by the ball to strike the ground is

    A
    `sqrt20s`
    B
    `2 sqrt20 s`
    C
    `4 sqrt20 s`
    D
    `10s`
  • A ball is thrown horizontally with a speed of 20 m//s from the top of a tower of height 100m velocity with which the ball strikes the ground is .

    A
    `20 sqrt6 m//s` at angle `tan ^(-10 (sqrt7)` below the horizontal
    B
    `20 sqrt6 m//s` at an angle `tan ^(-1) (sqrt6)` below the horizontal
    C
    `20 sqrt6 m//s` at an angle `tan ^(-1)(sqrt5)` below the horizontal
    D
    `10 sqrt6 m//s` at an angle `tan ^(-1) (sqrt5)` below the horizontal
  • Similar Questions

    Explore conceptually related problems

    A plane is flying horizontal at a height of 1000m with a velocity of 100 ms^(-1) when a bomb is released from it. Find (i) the time taken by it to reach the ground (ii) the velocity with which the bomb hits the target and (iii) the distance of the target.

    An enemy air plane is flying horizontally at an altitude of 2.7km with a speed of 250ms^(-1) .An army man on the ground observed it when it is directly over his head.He fired an anti-aircraft gun with a muzzle speed of 500ms^(-1) ,such that the shell hits the plane.At what angle with the horizontal,gun should be fired?

    A fightre plane flying horizontally at an altitude oa 1.5 km with speed 720 h^(-1) passes directly over head an anticraft gun. At what angle from the vertical should the gun be fired from the shell with muzzle speed 600 ms^(-1) to hit plane. At what minimum altitude showld the pilot fly the plane to avoid being hit ? ( Take g= 10 ms^(-2)).

    A cannon of mass 100 kg is kept on a frictionless floor. If a cannon ball of mass 1 kg is fired from it with a speed of 200 m/s. With what velocity the cannon will move ?

    A cannon of mass 100 kg is kept on a frictionless floor. If a cannon ball of mass 1 kg is fired from it with a speed of 200 m/s. With what velocity the cannon will move?

    An aircraft is .flying. horizontally with a constant vefocity =200m//s at a height =1km above groun At the momement shown, a bomb is released from the aircraft and the cannon-gun below fires a shell with initial speed =200m//s , at some angle theta For what value of theta will the projectile shell destroy the bomb in mid-air? If the value of theta is 53^(3) , find the minimum distance between the bomb and the shell as they fly past each other. Take sin53^(@)=4//5