Homework Help: Physics ~Work Kinetic Energy~

Posted by Isis on Wednesday, January 30, 2013 at 5:50pm.

1.)A ball (m 0.5 kg) starts from rest and has 300 J(joule) of work applied to it.

a) what is the initial kinetic energy of the ball?

b) what is the final kinetic of the ball?

c) what is the final velocity of the ball?

2.)A boy is doing chin-up. If the boy does 450 N of work to lift his body 0.25 m.

a) how much work does the boy do to lift himself up?

b) if he starts from rest, what his final kinetic energy?

c) what is the boy's final velocity?

>> FORMULAS <<
W= Fd
KE=1/2 v^2
PE= mgm
kg.m/s^2.m
kg.m^2/s^2=J

im sorry i don't know which formula to use. please help me! :)

Physics ~Work Kinetic Energy~ - Elena, Wednesday, January 30, 2013 at 6:15pm
a) KE₀=0
b) KE= 300 J
c) v=sqrt(2•KE/m)=…(m/s)

2)
a)W=mgh=450•0.25 = ... J
b) KE(fin) =0
c) v=0

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