Forces

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Forces
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Forces

• Force push or pull that acts on an object
• Forces cause
• Objects at rest to move
• Moving objects to accelerate by changing speed or
  direction

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Units of Force

• Newtons (N).
• 1 N force that causes a 1 kg mass to accelerate
  at a rate of 1m/s2
• Named after Sir Isaac Newton

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Representing Force

• Arrows indicate strength and direction of force
• Longer arrows larger force

larger force acting to the right
Force acting to the right
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Combining Forces

• Forces in the same direction add together
• 
  
• Forces in the opposite direction subtract
• Equal and opposite forces cancel

4N
2N
2N


2N
4N
2N


0
N
2N
2N
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• Net (resultant) Force Overall force acting on an
  object after combining all forces

3N
8N
1N
Net Force 4N to left
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Balanced Force

• Combined forces produce a net force of zero
• Object does not move

4N
4N
Forces are balanced
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Unbalanced force

• Produce net force not equal to zero
• cause objects to accelerate

3N
6N
6N
Object moves to the left net force 9N
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Friction

• Force that opposes motion
• Acts at surface where objects are in contact
• Friction produces heat
• Friction is higher on rough surfaces