Home > Physics > Conservation of Momentum

An astronaut with a mass of #75 kg# is floating in space. If the astronaut throws a #7 kg# object at a speed of #5/4 m/s#, how much will his speed change by?

Answer 1

Nathan Ashcroft

#vec v_a^'=-0.12" " m/s#

#"momentum before event:"# #.............................................#

#vec P_a=m_a*vec v_a" momentum of astronaut"# #vec P_a=75*0=0#

#vec P_o=m_o*vec v_o" momentum of object "# #vec P_o=7*0=0#

#Sigma P_b=0+0=0" total momentum"#

#"momentum after event:"# #...........................................#

#P_a^'=m_a*v_a^'# #vec P_a^'=75*vec v_a^'#

#vec P_o^'=m_o*vec v_o^'# #vec P_o^'=7*5/4=35/4" " kg*m/s#

#Sigma vec P_a=P_a^'+P_o^'# #Sigma vec P_a=75*vec v_a^'+35/4#

"Momentum is conserved in this event"

#Sigma vec P_b=Sigma vec P_a# #0=75*vec v_a^'+35/4#

#75*vec v_a^'=-35/4#

#vec v_a^'=-35/300#

#vec v_a^'=-0.12" " m/s#

By signing up, you agree to our Terms of Service and Privacy Policy

Answer 2

Adam Arnold

The astronaut's speed will change by approximately 0.015 m/s in the opposite direction of the thrown object.

By signing up, you agree to our Terms of Service and Privacy Policy

Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.