Physics
posted by Kaleigh .
A ball is thrown straight up from the ground
with an initial velocity of 30.4 m/s; at the
same instant, a ball is dropped from the roof
of a building 21.1 m high.
After how long will the balls be at the
same height? The acceleration of gravity is
10 m/s2.
Answer in units of s

d1 + d2 = 21.1 m.
(Vo*t  0.5g*t^2) + (0.5g*t^2) = 21.1,
The 2nd and 3rd terms cancel:
Vo*t = 21.1,
t = 21.1 / Vo = 21.1 / 30.4 = 0.694 s.
Respond to this Question
Similar Questions

physics
A ball is thrown upward from the ground with an initial speed of 26.2 m/s; at the same instant a ball is dropped from rest from a building 14 m high. After how long will the balls be at the same height? 
Physics
A ball is thrown upward from the ground with an initial speed of 21.5 m/s; at the same instant, a ball is dropped from rest from a building 17 m high. After how long will the balls be at the same height? 
physics
A ball is thrown upward from the ground with an initial speed of 26.7 m/s; at the same instant, a ball is dropped from a building 13.1 m high. After how long will the balls be at the same height? 
Physics
A ball is thrown upward from the ground with an initial speed of 23.1 m/s; at the same instant, a ball is dropped from a building 15.0 m high. After how long will the balls be at the same height? 
Physics
A ball is thrown upward from the ground with an initial speed of 25 m/s; at the same instant, a ball is dropped from rest from a building 15 m high. After how long will the balls be at the same height? 
physics
A ball is thrown upward from the ground with an initial speed of 25 m/s; at the same instant, a ball is dropped from rest from a building 15 m high. After how long will the balls be at the same height? 
Physics
A ball is thrown upward from the ground with an initial speed of 49 m/s; at the same instant, another ball is dropped from a building 16 m high. After how long will the balls be at the same height? 
Physics
A ball is thrown upward from the ground with an initial speed of 23.2 m/s; at the same instant, another ball is dropped from a building 20 m high. After how long will the balls be at the same height? 
Physics
A ball is thrown upward from the ground with an initial speed of 23.2 m/s; at the same instant, another ball is dropped from a building 20 m high. After how long will the balls be at the same height? 
physics2048
A ball is thrown straight up from the ground with an initial velocity of 43.5 m/s; at the same instant, a ball is dropped from the roof of a building 15.4 m high. After how long will the balls be at the same height?