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Newton's First Law
1/4
High Yield·21/28 papers · 6 years
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By the end of this lesson, you'll solve:

"Why do passengers lurch forward when a bus suddenly brakes?"

The Law of Inertia

Newton's First Law says: An object at rest stays at rest, and an object in motion stays in motion (at the same speed and direction), unless acted upon by an unbalanced force. Think of it like this - a cricket ball sitting on the ground won't move until you kick it, and once you hit a six, the ball would fly forever if air resistance and gravity didn't slow it down!

At restNo force = stays stillMovingv = constantNo net force = constant speedAn object stays at rest or in motion unless a force acts on it

Key Points

  • 1
    Objects resist changes in their state of motion - this resistance is called INERTIA
  • 2
    A body at rest tends to stay at rest (inertia of rest)
  • 3
    A body in motion tends to stay in motion (inertia of motion)

Pro Tip

Inertia is like laziness - objects don't want to change what they're doing!

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