## haridas_mandal 3 years ago Minimum velocity of a projectile is 20 m/s when a body is projected at an angle of 60 degree with the horizontal .Find the vel of projection....20 m/s,10 m/s,30 m/s or 40 m/s?

1. JamesWolf

so you want the horizontal velocity?

2. haridas_mandal

The question i have posted verbatim from my daughter's weekly test. I am not sure but there must be some conditionalities for 20 m/s to be the minimum velocity ..

3. JamesWolf

and there is no diagram or anything?

4. haridas_mandal

No none. Only 4 options as I noted above.

5. JamesWolf

it doesnt even have the word "the" at the start of the sentence? Perhaps she copied the question down wrong?

6. haridas_mandal

My mistake it should read "The Minimum.. I have the question paper right in front of me..

7. JamesWolf

and it just gives "find the vel of projection"?

8. haridas_mandal

It reads " The Minimum.....with the horizontal. The velocity of projection is 1) 20 m/s 2) 10 m/s 3) 30 m/s 4) 40 m/s "

9. JamesWolf

RIGHTTT thats much better. so the minimum velocity is 20m/s in the horizontal direction. find the absolute velocity. okay so i think it looks like this

10. JamesWolf

|dw:1350148494782:dw| your trying to find the hypotenuse

11. JamesWolf

yes, that gives an answer which is one of your possible answers

12. haridas_mandal

Her text book says there is a minimum velocity of projection to reach a specific point .I am not very satisfied taking 20 m/s as the vel in the horizontal direction. It should have been 20 Cos 60 as the horizontal component as it remains constant..is there any other possibility?

13. JamesWolf

wel in this isntance ? = 40 m/s

14. JamesWolf

what is the specific point?

15. haridas_mandal

How did you deduce? Pl help as I need to understand & then teach my daughter.

16. JamesWolf

Well I just found the hypotenuse of that triangle $velocity = hypotenuse = \frac{20 m /s}{\cos (60)} = 40 m/s$