AP Physics 1easymcq1 pt
A 70 kg astronaut floating in space throws a 2 kg wrench with a speed of 14 m/s. What is the recoil speed of the astronaut?
A.0.2 m/s
B.0.4 m/s
C.0.6 m/s
D.0.8 m/s
Explanation
Core Concept
Using conservation of momentum: m1v1i + m2v2i = m1v1f + m2v2f. (70)(0) + (2)(0) = (70)v1f + (2)(14). 0 = 70v1f + 28. -28 = 70v1f. v1f = -0.4 m/s. The negative sign indicates direction opposite to the wrench.
Correct Answer
B0.4 m/s
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