IIT JEE , AIEEE Forum - Physics , Mechanics - A ship is approaching a cliff of height 105m above the sea level . A gun fitted on the shi

anoopsant

A ship is approaching a cliff of height 105m above the sea level . A gun fitted on the ship can fire shots with a speed of 110m/s.Find the maximum distance from the foot of the cliff from where the gun can hit an object on the top of the cliff??

karthik2007

Its a simple case of projectile motion...

See, here, use y=xtan@ - gx^2/2u^2cos^@

y = 105m, u=110m/s, maximize x and proceed.

krishna.gopal

Perfect answer Karthik. Well done

rakhiagrawal

what value of @ should be taken?

rooney

For the greatest value of distance from the foot of the cliff x, the bullet should JUST hit the object. So, the maximum height of the projectile should be 105m.

So, you get Sin

..

x is 105Cot

Calculations are hard though.

rakhiagrawal

i agree with u.but 2 things are unknown to calculate the value of x.
1.@
2.hypotenuse
if we know either of them we can calculate it.but still it is not that clear to me.

rooney

No. to find the angle, you use that condition that 105 is the max height reached. Since we know u, we get the angle. and thus x.

rakhiagrawal

oh.u mean we can take
Hmax=u^2sin^2@/2g & Hmax=105 & can get the value of @.then i got it.thans.

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