AP Physics 1hardmcq1 pt
Two crates (A = 3.0 kg in front, B = 2.0 kg behind) are pushed in a line by 20 N on B across frictionless ice. The force of A on B is
A.12 N
B.20 N
C.8.0 N
D.4.0 N
Explanation
Core Concept
System acceleration a = 20/5 = 4.0 m/s². A needs 12 N to accelerate, and that force comes from B pushing A (so A pushes back on B with 12 N).
Correct Answer
A12 N
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