An object is thrown vertically from a height of #7 m# at # 3 m/s#. How long will it take for the object to hit the ground?
1 Answer
Explanation:
We're asked to find the time
As soon as the object is let go, it is in a state of free-fall, and the kinematics equations can predict its motion, such as its maximum height reached, time of flight, etc.
To find this time, we can use the equation
For this equation,
-
The height
#y# is ground level, which I'll call#0# #"m"# -
The initial
#y_0# is#7# #"m"# -
The initial
#y# -velocity#v_(0y)# is#3"m"/"s"# -
The time
#t# is when it is at height#y = 0# , which is what we're trying to find -
The
#y# -acceleration#a_y# is equal to#-g# , which is#-9.8"m"/("s"^2)#
Plugging in our known values, we have
Using the quadratic formula:
Thus, the object will strike the ground after