Physics kinematics and dynamics problem!?

R

Roy W

New member
the question is 'while on a ride, you drop an object. the vehicle you were in was traveling 11.0 m/s, and was 5.0 m above the ground at the time of the drop. how long does it take for the object to reach the ground?'

i have
Vi = 11.0 m/s
D = 5 m
a (or g) = -9.81 m/s²
t = unknown

given the formula d=Vi(t) + (1/2)(a)(t²)

i need to find time, i cant seem to isolate the t variable please help!
it gave the answer - 2.6 seconds. just not how to get it.
also, it was traveling 11.0 m/s at the Vi, as the vehicle was already moving at that speed. not at 0
 
goodness! such a mess up of physics! however fast the ride goes, it is along the horizontal and cos90=0. so the vertical acceleration is always the same.approximately 1.you're welcome.
 
here's your problem...i had this with physics too, think of it in 2 dimenisons horizontal and vertical your horizontal variables are

Vi= 11.0 m/s
D= ? (D is given in vertical direction
a= 0 m/s (gravity is in vertical direction)


for vertical
Vi= 0 m/s (before the ball was dropped it was moving at 0 m/s downward)
D= 5 m
a= -9.8 m/s^2

start with vertical components

x= vot +1/2at^2 so then you get 1/2(9.8)t^2= 5 t= 1.01 secs

(you don't need the 11.0 unless you wanted to figure out where on the ground the ball landed)
 
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