An astronaut with a mass of $80 k g$ $80 kg$ is floating in space. If the astronaut throws an object with a mass of $15 k g$ $15 kg$ at a speed of $\frac{2}{5} \frac{m}{s}$ $2/5 m/s$ , how much will his speed change by?

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Answer 1 · 2016-05-20T11:51:07

$v_a^'=-0.93" " m/s$

$m_a:"mass of astronaut"$
$v_a:"velocity of astronaut"$
$m_o:"mass of object"$
$v_o=:velocity of object"$

$Sigma P_b:"total momentum before event"$

$Sigma P_b=m_a*v_a+m_o*v_o$
$Sigma P_b=80*0+15*0=0$

$"Total momentum after event "$

$Sigma P_a=m_a*v_a^'+m_o*v_o^'$
$Sigma P_a=80*v_a^'+cancel(15)*2/cancel(5)$
$Sigma P_a^'=80*v_a+6$

$"Sigma P_b=Sigma P_a$
$0=80*v_a^'+6$

$80*v_a^'=-86$

$v_a^'=-80/86$

$v_a^'=-0.93" " m/s$

An astronaut with a mass of 80 kg80kg80 kg is floating in space. If the astronaut throws an object with a mass of 15 kg15kg15 kg at a speed of 2/5 m/s25ms2/5 m/s, how much will his speed change by?