Ann the Astronaut weighs 60 kg.She is space walking outside the space shuttle and pushes a 350-kg satellite away from the shuttle at 0.90 m/s.What speed does this give Ann as she moves toward the shuttle?
A)4.0 m/s
B)5.3 m/s
C)8.5 m/s
D)9.0 m/s

Question

Quizplus · Accepted Answer

By conservation of momentum, we have:

Ann's momentum before pushing the satellite = Ann's momentum after pushing the satellite

Initial momentum of Ann = mv; where m is Ann's mass (60 kg) and v is Ann's velocity before pushing the satellite (unknown)

Final momentum of Ann = (m + M)V; where M and V are the mass and velocity of the satellite after it was pushed away (M = 350 kg, V = -0.90 m/s since the satellite moves away from Ann)

Since momentum is conserved, we have:

mv = (m + M)V
v = (m + M)V/m

Plugging in the numbers, we get:

v = (60 kg + 350 kg)(-0.90 m/s)/60 kg = -5.3 m/s

The negative sign indicates that Ann is moving in the opposite direction to the satellite (i.e., towards the shuttle). Taking the absolute value, we get:

|v| = 5.3 m/s

Therefore, the answer is B.

Ann the Astronaut Weighs 60 Kg