# Question #6624a

##### 1 Answer

Jan 28, 2018

- Total energy at the top of cliff
#mgh=20000J#

Inserting various values and taking#g=10ms^-2#

#50xx10xxh=20000#

#=>h=20000/(500)=40m#

(matches with the given number in the text. - Half way down
#1/2# of her energy has been converted in to her kinetic energy. If#v# is her velocity half way down we get

#1/2mv^2=10000#

#=>v^2=10000xx2/50=400#

#=>v=sqrt400=20" ms"^-1#