Newtons first law of motion An objects speed

• 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.

• 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 (1 st Law of motion) • They always act in certain direction • A newton meter is used to measure forces.

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.

Balanced and Unbalanced Forces Balanced Forces produce Unbalanced Forces NO change in Movement Change the Speed and or Direction of Moving Objects The forces on the person are balanced The floor pushes upward on the person Gravity pulls downwards on the person Smaller Force Greater Force

Forces & Movement Forces are nearly always PUSHES and PULLS

Forces can make objects do FIVE things 1. Speed up 2. Slow down 3. Change Direction Like kicking a ball Like drag or air resistance Like hitting a ball with a bat 4. Turn Like turning a spanner 5. Change shape Like stretching, twisting, compressing and Bending

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

Show the forces acting on the Owl sitting and reading Is the force acting on the Owl balanced or unbalanced?

Think about this situations If 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?

Where are the forces acting on this clock

Where are the forces acting?

Where are the forces acting?

Where are the forces acting?

Where are the forces acting?

Where are the forces acting?

Where are the forces acting? Look carefully at the insect and the frog

Where are the forces acting? Look carefully at the motion of the ball Iffat Sardharwalla March 2010