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Physics · Chapter 4: Forces and Newton's laws

Year 11 Science · About 16 minutes with activities · Turn your sound on

Chapter 4 · Forces and Newton's laws
The paddles stop……and the waka slows to a stop
Thrust = dragbalanced forces: a steady speed
Force sandboxyou set the thrust and the friction
Equal and oppositeacting on different objects

Chapter 4 recap

  • Force: a push or a pull on an object that results in a change in speed, shape or direction (newtons, N). Contact: support, thrust, friction/drag/air resistance, buoyancy, tension, lift. Non-contact: magnetic, electrostatic, weight.
  • Balanced forces (net force 0): motion doesn’t change, so the object stays at rest or keeps a constant speed. Unbalanced: net force with the motion → accelerates; against the motion → decelerates.
  • Newton’s laws: 1. inertia · 2. Fnet = ma (a = F ÷ m, m = F ÷ a) · 3. A on B ⇒ B on A, equal and opposite. Find the net force first.
  • Next: Chapter 5 · Mass, weight, friction and pressure

Do you need a force just to keep something moving?

Chapter 4 · About 16 minutes · sound on

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