## anonymous 4 years ago A projectile is thrown horizontallly from the top of a tower and strikes teh ground after 3 second at an angle of 45 degrees with the horizontal. Find the height of the tower and speed with which the body was projected. (Take "g" = 9.8 m/s^2)

• This Question is Open
1. anonymous

2. anonymous

3. anonymous

what is angle of projection? is the question written as it is?

4. anonymous

Yeah, the question is as it is as I have written here.

5. anonymous

k

6. anonymous

So when it strikes, basically the horizontal and vertical components of its velocity are equal (since it strikes the ground at 45 degrees) Now, let the initial velocity of projection be 'u' Now, the horizontal speed remains constant, but the vertical component increases from '0' to 'u', as it hits the ground. Now, vertical component (final) = v time of flight = sqrt(2gh) = 3 Find height, and then find 'u'.

7. anonymous

How time of flight = sqrt(2gh)? Can u show the complete steps and other equations also?

8. anonymous

LOL sorry - it would 'final' velocity, not time of flight - my bad lol.

9. anonymous

Still i am not able to follow how is it equal to sqrt(2gh)? Can u show the workign of other steps also?

10. anonymous

yeah, so use, (v-u)/g = t

11. anonymous

hey is the speed 97 ? u know the answers?

12. anonymous

13. anonymous

for a particle under free fall with initial velocity 'u=0'|dw:1338565657495:dw|

14. anonymous

Got it. Can we not say that:$T = 2u \cos \theta / g = \sqrt{2}u/g$

15. anonymous

yeah, v=30, and height = 45 metres, right?

16. anonymous

well, that is for a ground-to-ground projectile @Aadarsh

17. anonymous

@apoorvk bhai, ur answer is right.

18. anonymous

@apoorvk bhai, please show all the steps.

19. anonymous

look the pa

20. anonymous

Thanks apoorv bhai.

21. anonymous

See, ye samajh mein aaya ki horizontal and vertical components at the time of hitting the ground same honge?

22. anonymous

Yeh to samajh mein nahion aaya.....

23. anonymous

samjha dijiye

24. anonymous

see the attachment koi horizontal equal lene ki jarurat nh ihai

25. anonymous

samajh aaya?

26. anonymous

isse pahle bhi ek attachment tha jisme U nikaala hai , dkho, Final velocity to 0 hi hoga naa jab wo gir jaaye to

27. anonymous

Thakns srini bhaiiiiiiiii. samajh mein aa gaya.

28. anonymous

k good

29. anonymous

Sri, great calligraphy! :P

30. AravindG

srry i am late :P

31. anonymous

ha ha