The 3 Laws of Sir Isaac Newton And you

Historical Background Isaac Newton 1642 – 1727 Developed first reflecting telescope Demonstrated that white light is composed of all colors of light (using a prism) Developed integral calculus And more…

Newton’s 1 st Law: Inertia An objects will remain at rest – or in uniform motion – unless acted upon by an external force. Demos here – Standing car, F on car to move, F on car to stop, barbie w/o seatbelt, Barbie w/ seat belt, F on Ken, scooter –vs- air platform

Newton’s 2 nd Law: F = ma Force = (mass) (acceleration) The magnitude of acceleration of an object depends on the mass of the object, and the magnitude of force acting on the object Demos here- car alone a – (calculation), car with brick a, small person on cart –vs- lg person on cart

Newton’s 3 rd Law: Action/Reaction For every action, there is an equal and opposite reaction Demos here – cart and wall, 2 carts 1 push, 2 carts 2 pushes, platform w/ heavy backpack throw

Conceptual question #1 If an elephant and a mouse are moving toward you at the same velocity in outer space. Will they have the same effect on you when they bump into you???? NO! More mass = more inertia = elephant gives bigger bump!

Question 2 If the space elephant was chasing you here on planet Earth why would running in a zig-zag pattern be to your advantage? More mass = more inertia = harder to change directions = your advantage to have less mass! Show chase video if time allows

Question 3 You are back in outer space and have 2 identical closed containers. One is filled with feathers, the other with lead. How can you tell which one has the feathers? Move them – and stop them. It will be more difficult to make the container with lead accelerate (requires more force). It will also be more difficult to de-accelerate (and stop) that lead filled container.

Question 4 You have a ball in a wagon. You accelerate the wagon forward rapidly. Describe the motion of the ball relative to the ground. The ball remains in the same place relative to the ground Describe the motion of the ball relative to the floor of the wagon The ball moves to the back of the wagon

Question 5 Some people believed that you could not make a rocket go to the moon – because there is no atmosphere in space. What force makes a rocket move forward in space? Action/reaction! The expanding gases that are pushed out of the rocket – push the rocket in the opposite direction.