What is the kinetic energy of an object with a mass of #5 kg# that has been in freefall for #7 s#?

1 Answer
Apr 24, 2018

Answer:

see below

Explanation:

#KE=1/2mv^2#

where the letters take their usual meaning

we need to find the velocity after #7s#
#t=7s#
#u=0ms^(-1)#

#v=?#

#g=9.8ms^(-2)#

#v=u+at#

#v=0+9.8xx7=68.6ms^(-1)#

#:.KE=1/2xx5xx68.6^2#

#KE=11764.9=11800J#(3sf)