H2 Physics 4 - Energy and Fields: Work-Energy Theorem on a Rough Surface

What you will learn

• 3 kg box pushed by 20 N at 15 degrees above horizontal on a rough floor with mu_k = 0.25, from rest, over 4 m.
• Vertical balance: N = mg minus F sin theta = 29.43 minus 5.18 = 24.2 N; the upward push component reduces N.
• Friction f = mu_k N = 6.06 N opposes motion; horizontal push = 20 cos 15 = 19.3 N.