Iffat Sardharwalla Mar ch 2010 • Newton’s first law of motion : An object’s speed will only change if a force is applied. • Newton’s second law of motion: Speed or acceleration is proportional to the force. • Newton’s third law of motion : Every action has an equal and opposite reaction.
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Iffat Sardharwalla March 2010
• Newton’s first law of motion: An object’s speed will only change if a force is applied.
• Newton’s second law of motion: Speed or acceleration is proportional to the force.
• Newton’s third law of motion: Every action has an equal and opposite reaction.
Iffat Sardharwalla March 2010
• Forces can’t be seen, but the effect of a force can be seen.
• They are measured in newtons – N
• They usually act in pairs (1st Law of motion)
• They always act in certain direction
• A newton meter is used to measure forces.
Iffat Sardharwalla March 2010
Two things make up a force
1. its size, how strong a push or pull is, and
2. its direction, which way it pushes or pulls.
We draw forces as arrows.
1. The length of the arrow shows how strong the force is and 2. way it points shows the direction of the force.
Iffat Sardharwalla March 2010
Balanced Forces produce
NO change in Movement
Unbalanced Forces
Change the Speed and or
Direction of Moving Objects
Balanced and Unbalanced Forces
The forces on the person are balanced
The floor pushes upward on the person
Gravity pulls downwards on the
person
Greater Force
Smaller Force
Iffat Sardharwalla March 2010
Forces & MovementForces are nearly always
PUSHES and PULLS
Iffat Sardharwalla March 2010
Forces can make objects do FIVE things
1. Speed up
Like kicking a ball
2. Slow down
Like drag or air resistance
3. Change Direction
Like hitting a ball with a bat
4. Turn
Like turning a spanner
5. Change shape
Like stretching, twisting, compressing and Bending
Iffat Sardharwalla March 2010
Look at some of the forces in action
• Are they Balanced or Unbalanced?
Tasks
Now draw the arrows to show the
• Direction of the forces
• Strength of the forces
Iffat Sardharwalla March 2010
Show the forces acting on the Owl sitting and reading
Is the force acting on the Owl balanced or unbalanced?
Iffat Sardharwalla March 2010
Think about this situationsIf you were pushing these elephants to move…1. Which will need more force to move? Why? 2. Which direction would they be travelling? Why?3. Which elephant will move faster? Why?
Iffat Sardharwalla March 2010
Where are the forces acting on this clock
Iffat Sardharwalla March 2010
Where are the forces acting?
Iffat Sardharwalla March 2010
Where are the forces acting?
Iffat Sardharwalla March 2010
Where are the forces acting?
Iffat Sardharwalla March 2010
Where are the forces acting?
Iffat Sardharwalla March 2010
Where are the forces acting?
Iffat Sardharwalla March 2010
Where are the forces acting? Look carefully at the insect and the frog
Iffat Sardharwalla March 2010
Where are the forces acting?Look carefully at the motion of the ball
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