While on an interplanetary mission, a 58.5-kg astronaut is floating toward the front of her ship at 0.15 m/s, relative to the ship. She wishes to stop moving, relative to the ship. She decides to throw away the 2.50-kg book she's carrying. What should the approximate speed and direction of the book be to achieve her goal?
A)0.15 m/s, toward the front of the ship
B)3.5 m/s, toward the back of the ship
C)3.7 m/s, toward the front of the ship
D)0.30 m/s, toward the back of the ship
E)1.5 m/s, toward the front of the ship

Question

Quizplus · Accepted Answer

According to the law of conservation of momentum, the total momentum of the system (astronaut + book) must be zero. Initially, the astronaut has a momentum of -0.15 m/s * 58.5 kg = -8.775 kg m/s. To stop moving, she must throw the book in the opposite direction with a momentum of 8.775 kg m/s. The mass of the book is 2.50 kg, so its speed must be 8.775 kg m/s / 2.50 kg = 3.51 m/s. The direction of the book must be toward the back of the ship, so the correct answer is B) 3.5 m/s, toward the back of the ship.

While on an Interplanetary Mission, a 58