Problema Solution
a rock is thrown upward with a velocity of 22 meters per second from the top of a 35 meter high cliff and it misses the cliff on the way back down. when will the rock be 7 meters from the water below?
Answer provided by our tutors
The position of the rock is
s(t) = (-1/2)g*t^2 + 22*t + 35
where g is the acceleration due to gravity and g= 9.81 m/s2
we want to find t such that s(t) = 7 thus we have
(-1/2)g*t^2 + 22*t + 35 = 7
(-1/2)(9.81)*t^2 + 22*t + 35 = 7
by solving the quadratic equation we find and consider only the positive roots (time can not be negative)
t = 5.52 sec
click here to see the step by step solution of the equation
the rock will be 7 meters from the water after 5.52 seconds.