An astronaut with a mass of #80 kg# is floating in space. If the astronaut throws an object with a mass of #12 kg# at a speed of #2 m/s#, how much will his speed change by?

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Answer 1 · 2016-06-03T11:35:11

#v_a^'=-0.3" "m/s#

#"Total momentum before event is zero"#

#m_a=80" "kg" ; "v_a=0#

#m_o=12" "kg" ; "v_o=2" "m/s#

#P_b=m_a*v_a+m_o*v_o#

#P_b=80*0+12*0=0#

#"Total momentum after is :"#

#P_a=m_a*v_a^'+m_o*v_o^'#

#P_a=80*v_a^'+12*2#

#P_a=80*v_a^'+24#

#P_b=P_a" momentum is conserved "#

#0=80*v_a^'+24#

#80*v_a^'=-24#

#v_a^'=-24/80=3/10=-0.3#

#v_a^'=-0.3" "m/s#