How high is the building?

  • Thread starter wellojello
  • Start date
  • #1
greetings :)

so i'm pretty stumped on this one question from masteringphysics:

A ball thrown horizontally at 23.7 m/s from the roof of a building lands 35.0 m from the base of the building. How high is the building?

i first listed all of my given values
---------------------------
v_x0 = 23.7 m/s
a = a_y = -g = -9.8 m/s^2
x = 35 m
x_0 = y_0 = 0
v_y0 = 0
a_x = 0
t = ?
y = ?
---------------------------

used the horizontal motion formula to find t

x = x_0 + v_x0 t + 1/2a_x t^2
t = 35/23.7 = 1.5s

and then the vertical motion formula to find y with the time i found above

y = y_0 + v_y0 t - 1/2gt^2
y = -1/2 (9.8)(1.5^2)
y = 11.025m

---------------------------

they said that this answer is "not quite", but i went over my calculations and still got 11.025 m. did i plug in the wrong values or used the wrong formulas?

thanks!
 

Answers and Replies

  • #2
i just realized i've posted this onto the wrong thread. my apologies
 

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