+2863 The CN tower is 533 meters tall.
a) If a heavy rock is dropped from the tower, how long will it take to hit the ground?
b) What is its velocity the instant it hits the ground? (Not 0, the instant before it it hits the ground)
I wrote up an explanation in this google document on my attempt
https://docs.google.com/document/d/1mi5p3SrO_MEV3VdqbpHTNhaY2UKbWdJR7_oTeO-Lqrs/edit?usp=sharing
Apparently one of my classmates said my solution is wrong, and this is his explanation:
so
Distance:D
Initial velocity is Vi
Final Velocity is Vf
time is T
acceleration is A
and average velocity is Vavg
so
D=Vavg*T
Just the definition of average velocity
D=1/2(Vi+Vf)*t
because 1/2(Vi+Vf) is always average velocity under constant acceleration (It helps to pause and think about it)
D=1/2(Vi+Vi+at)*t
the final velocity is just the change in velocity(a*t) plus the original velocity
D=1/2(2*Vi+at)*t
Combine like terms
D=Vi+1/2*a*t^2
distribute the 1/2
now you plug in the values and solve
10.4295498562537027982 should be the answer
Who is right? What is wrong with my method if I am wrong? What is wrong with his method if HE is wrong?
+2863 Oh ok! I will always trust a systems engineer (i think thats what you are if my memory serves me correctly)
Aren't these the standard equations of free falling bodies?
Distance d, travelled by an object falling for time t.
d = 1/2 * g * t^2
533 =1/2 * 9.81 * t^2
t =10.424 seconds
Instantaneous velocity v of a falling object that has travelled distance d :
v =Sqrt(2 * g * d)
v =Sqrt(2 * 9.81 * 533)
v =102.262 m/sec
+2863 We actually haven't learned these equations
we only learned acceleration and velocty formulas.
That problem was a challenge because we were supposed to "discover" these equations on our own.
im in 8th grade its all new tah meh
+700 rip i remember that nasty velocity and acceleration stuff from last year and i did not like it at all
lol........physics is definitely not my best subject :_ (
+2863 I like Physics, only because it has so much to do with math. Except when the teacher gives me a bad grade XD (happening right now I have a solid B+)
