Question
You are standing at the foot of the Bank of America building in San Francisco, which is 52 floors (237 m) high. You launch a ball straight up in the air from the edge of the foot of the building. The initial vertical speed is 70 m/s.
a. How high up does the ball go?
b. How fast is the ball going right before it hits the top of the building?
c. For how many seconds total is the ball in the air?
(Not sure which equation to use, that's the main reason why I'm asking the question. I don't want to use the wrong equation.)
a. How high up does the ball go?
b. How fast is the ball going right before it hits the top of the building?
c. For how many seconds total is the ball in the air?
(Not sure which equation to use, that's the main reason why I'm asking the question. I don't want to use the wrong equation.)
Answers
a. Use conservation of energy. The ball rises to a maximum height H such that
gH = Vo^2/2
H = (1/g)*(1/2)*Vo^2 = 250 m
Vo is the initial velocity that it is thrown.
b. At the top of the building, where Y = 237 m,
Vo^2/2 = V^2/2 + g*Y
Solve for V
V^2/2 = (1/2)(4900)-(g*237)
= 2450 - 2323 = 127 m^2/s^2
V = 15.9 m/s
c. It takes Vo/g = 7.14 s to go up and the same time to come down.
gH = Vo^2/2
H = (1/g)*(1/2)*Vo^2 = 250 m
Vo is the initial velocity that it is thrown.
b. At the top of the building, where Y = 237 m,
Vo^2/2 = V^2/2 + g*Y
Solve for V
V^2/2 = (1/2)(4900)-(g*237)
= 2450 - 2323 = 127 m^2/s^2
V = 15.9 m/s
c. It takes Vo/g = 7.14 s to go up and the same time to come down.
Related Questions
a chimney of 20m height standing on the top of a building subtends an angle whose tangent is 1/6 at...
Standing on the top of a building, Eric spots his friend's car at an angle of depression of 35°. T...
A boy is standing at the top of the a building, 40 m high. He leans over the side and throws a pebbl...
A man standing on top of a 100 foot building sites the top of a nearby building at an angle of eleva...