a particle at a height h from the ground is projected with an angle 30 degree from the horizontal,it strikes the ground making 45degree with the horizontal.it is again projected from these point with same speed but with an angle of 60 degree find the angle it makes with the horizontal when it strikes the ground;..................................options....a tan(5)..b tan(root 5)....c tan(root 3)

Asked by meet | 17th Sep, 2012, 04:09: PM

Expert Answer:

horizontal initial velocity=horizontal final velocity
u cos30=v cos45............(1)
v=(u cos30)/cos45.....(2)
v2 sin245=u2 sin230+2gh.......(3)
putting value of v in (3):
2gh=u2 (cos2 30-sin230)....(4)
 
in the second case:
horizontal initial velocity=horizontal final velocity
u cos60=v cos?............(5)
v=(u cos60)/cos?.....(6)
v2 sin2?=u2 sin260+2gh.......(7)...as the height remains same.
putting value of v in (8):
2gh=u2 (tan2?cos2 60- sin260)....(9)
putting 2 gh value from (4) in (9) and hence solving:
tan2?=5
?=tan-1 ?5
 

Answered by  | 20th Nov, 2012, 03:12: PM

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