projectile Q (1 Viewer)

[haboozin]

A ball is thrown from a window that is 16m from the ground. of the angle of projection is 60 degrees, initial velocity is 6m/s and assume g = 10m/s^2 find
a. thetime taken for the ball to land
b. how far the ball will land from the base of the building..


Please use physics formula's to solve this... no deriving (i know the maths way is better and logical)

also i dont see the EQ r=ut +1/2at^2 in our formula sheet so avoide using it.
http://www.boardofstudies.nsw.edu.au/syllabus_hsc/pdf_doc/physics_formulaesheet.pdf

 

[acmilan]

That formula is the most basic and most used one in projectile motion and kinematics in general and is actually on the sheet. Its written as delta y = ut +1/2at². Delta y just means the change in vertical position, also written as S_y by some books.

A ball is thrown from a window that is 16m from the ground. of the angle of projection is 60 degrees, initial velocity is 6m/s and assume g = 10m/s^2 find
a. thetime taken for the ball to land
b. how far the ball will land from the base of the building..

U_x = 6cos60 = 3 ms^-1
U_y = 6sin60 ms^-1(leave it like this as its irrational)

(a) when s = -16 m (ie its at the ground)

S_y = U_yt + 1/2(at²)
- 16 = 6sin60t - 1/2(10*t²) (both a and s are negative as up is taken as positive)
5t² - 6sin60t - 16 = 0

Solving using quadratic formula gives t = 2.4 seconds (ignore second answer as it is negative)

(b)
When t = 2.4 seconds,

S_x = U_xt
S_x = 3*2.4
S_x = 7.15 m from the base of the building

 

[haboozin]

thnx, jeez i was doing that but i accidently left it as positive n the quad wasnt a real number so i was like :| i must be doing something wrong :'(