First Law of Thermodynamics Video Lessons

Concept

# Problem: A skater pushes straight away from a wall. She pushes on the wall with a force whose magnitude is F, so the wall pushes on her with a force F (in the direction of her motion). As she moves away from the wall, her center of mass moves a distance d. Consider the following statements regarding energy. I ΔKtrans + ΔEinternal = Fd II. ΔKtrans + ΔEinternal = −Fd III. ΔKtrans + ΔEinternal = 0 IV. ΔKtrans = Fd V. ΔKtrans = −Fd What is the correct form of the energy principle for the skater as a real system and as a point particle (PP) system? 1. Real: II, PP: V 2. Real: I, PP: V 3. Real: II, PP: IV 4. Real: V, PP: I 5. Real: IV, PP: III 6. Real: III, PP: IV 7. Real: V, PP: IV 8. Real: I, PP: IV 9. Real: III, PP: V 10. Real: IV, PP: IV

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###### Problem Details

A skater pushes straight away from a wall. She pushes on the wall with a force whose magnitude is F, so the wall pushes on her with a force F (in the direction of her motion). As she moves away from the wall, her center of mass moves a distance d. Consider the following statements regarding energy.

I ΔKtrans + ΔEinternal = Fd
II. ΔKtrans + ΔEinternal = −Fd
III. ΔKtrans + ΔEinternal = 0
IV. ΔKtrans = Fd
V. ΔKtrans = −Fd

What is the correct form of the energy principle for the skater as a real system and as a point particle (PP) system?

1. Real: II, PP: V
2. Real: I, PP: V
3. Real: II, PP: IV
4. Real: V, PP: I
5. Real: IV, PP: III
6. Real: III, PP: IV
7. Real: V, PP: IV
8. Real: I, PP: IV
9. Real: III, PP: V
10. Real: IV, PP: IV