• Newton’s Cradle (a desk toy with a series of spheres suspended in a line) is a great visual example of momentum transfer.
• Momentum, symbolized by p, is transferred when a moving sphere hits another sphere, causing it to move.
• This is a type of collision, defined as any interaction where momentum is transferred or shared between moving objects.
• Real-life examples include firing a gun, hitting a ball with a bat, toy cars crashing, or a pile driver at a construction site.

✏️ Fun Fact: The Newton's Cradle wasn't invented by Newton but serves as an excellent example of his laws of motion in action!

• The change in velocity of colliding objects can be viewed as a change in momentum or the effect of a force acting for a certain time.
• This involves a quantity known as impulse, represented by J.
• We can derive a new equation from Newton's second law of motion (F = ma), substituting a with (v - u) t (change in velocity over time).
• This leads to F = m \(\frac{v\ -\ u}{t}\) or F = \(\frac{Δp}{Δt}\)  which interprets as force equals change in momentum over the time taken for change.
• Impulse is the product of force F and time Δt over which the force acts - J = FΔt.
• The units of impulse are Newton seconds (Ns), equivalent to change in momentum, giving us another unit for momentum.

✏️ Real-World Example: A small group of people can push a heavy vehicle to get it moving. They exert a small force over a long time, similar to how impulse works!

Example

• An impulse of 85 Ns acts on a body of mass 5.0 kg initially at rest. The final speed is \(\frac {85}{5} = 17 \frac {m}{s}\). In 2.0 seconds, the distance travelled is 34 m.

Example

• A ball of mass 0.40 kg moves at a right angle to a wall, hitting the wall at a speed of 9.0 m/s and rebounds at a speed of 6.0 m/s in 50 ms.
• The acceleration of the ball and the force between the ball and the wall need to be calculated.