A Machine Gun Is Attached to a Railroad Flatcar That

question 29

Multiple Choice

A machine gun is attached to a railroad flatcar that rolls with negligible friction.If the railroad car has a mass of 7 × 10⁴ kg,how many bullets of mass 20 g would have to be fired at 200 m/s off the back to give the railroad car a forward velocity of 0.5 m/s?

• A) 8.8
• B) 0.11
• C) 1,400
• D) 8,750
• E) ​14

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Definitions:

Self-serving Bias

A cognitive bias that involves attributing positive outcomes to oneself and negative outcomes to external factors.

Spotlight Effect

The belief that others are paying more attention to one's appearance and behavior than they really are.

Self-efficacy

Self-efficacy refers to an individual's belief in their capacity to execute behaviors necessary to produce specific performance attainments.

Defensive Self-esteem

A form of self-esteem characterized by a fragile sense of self that is highly sensitive to perceived criticism or threat.