Automatic door closing 0.2m/s,with a kinetic energy of 1.6j?

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Answer 1 · 2018-05-01T18:28:10

#80kg#

#KE = 1/2mv^2#

where

#KE# is kinetic energy in joules #J#

#m# is mass in kilograms #kg#

#v# is velocity in metres per second #m//s#.

i assume that you want to find the door's mass, as that is the only quantity in the kinetic energy equation which is not mentioned.

here, #KE = 1.6J# and #v = 0.2 m//s#.

#1/2 mv^2 = 1.6#

#mv^2 = 3.2#

#v^2 = 0.2^2 = 0.04#

#mv^2 = 0.04m = 3.2#

#m = 3.2/0.04 = 80#

hence, #m = 80 kg#.

the mass of the door is #80kg#.