A marble dropped from a bridge strikes the water in 5.0 s. what is the height of the bridge? (Answer in meters)A

1 Answer
Jun 6, 2018

#"122.5 m"#

Explanation:

Use equation of motion

#"S" = "ut" + 1/2"at"^2#

Where

  • #"S ="# Displacement covered
  • #"u ="# Initial velocity
  • #"a ="# Acceleration (It’s #"9.8 m/s"^2# due to Earths gravity)
  • #"t ="# Time taken to cover displacement #"S"#

Marble is dropped. It means initial velocity (#"u"#) of marble is #0#

Therefore the equation becomes

#"S" = 1/2"at"^2#

#color(white)("S") = 1/2 × "9.8 m/s"^2 × "(5 s)"^2#

#color(white)("S") = 122.5\ "m"#

Displacement covered by the marble when thrown from the bridge is obviously height of the bridge.