Question

a gun kept on a straight is used to hit a car travelling along the same road away from the gun with the uniform speed of 72km/hr. the car is at a distance of 500m form the gun when the gun is fired at the angle of 45 with the horizontal find the distance of the car from the gun when the shell hits it

Answer 1

Explanation:

ANSWER

Let the speed of the shell fired from the gun be 'v'

s

m

Angle at which the shell is fired = 45

∘

Time of flight of the shell =

g

2vsinΘ

=

g

2vsin(45

∘

))

=

g

v

2

Distance covered by car during this time = 20*t

= 20*

g

v

2

Range of shell =

g

v

2

sin(2Θ)

=

g

v

2

For the shell to hit the car,

160 + 20t =

g

v

2

160 + 20*

g

v

2

=

g

v

2

Take g = 10

s

2

m

We get v = 40

2

s

m

Hence, distance of the car from the gun when the shell hits it = 160 + 20t

= 320 m

And, speed of projection from the gun = 40

2m/s