🎉 Announcing Numerade's $26M Series A, led by IDG Capital!Read how Numerade will revolutionize STEM Learning California State Polytechnic University, Pomona ### Problem 71 Easy Difficulty # A railroad hopper car filled with sand is rolling with un initial speed of 15.0$\mathrm{m} / \mathrm{s}$on straight, horizontal tracks. You can ignore frictional forces on the railroad car. The total mass of the car plus sand is$85,000 \mathrm{kg}$. The hopper door is not fully closed so sand leaks out the bottom. After 20$\mathrm{min}$,$13,000 \mathrm{kg}$of sand has leaked out. Then what is the speed of the railroad car? (Compare your analysis with that used to solve Exercise$8.27 . )$### Answer ## 15.0$\mathrm{m} / \mathrm{s}\$

#### Topics

Moment, Impulse, and Collisions

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##### Christina K.

Rutgers, The State University of New Jersey

##### Marshall S.

University of Washington

##### Aspen F.

University of Sheffield

Lectures

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### Video Transcript

California State Polytechnic University, Pomona

#### Topics

Moment, Impulse, and Collisions

##### Christina K.

Rutgers, The State University of New Jersey

##### Marshall S.

University of Washington

##### Aspen F.

University of Sheffield

Lectures

Join Bootcamp