Lesson link A balloon is filled up with hydrogen gas and then is released before being tied, explain why the balloon accelerates using Newton’s laws of motion

Draw a line under last lesson’s work and write today’s title in your book... 19/11/2018 c/w Momentum

Engage Watch this video and then explain the following… Why does the snowball get harder to stop?

Securing (4-6) Describe examples of momentum in collisions Learning Objectives Developing (3) Define momentum, recall and use the equation (momentum = mass x velocity) Securing (4-6) Describe examples of momentum in collisions Exceeding (7-9) Apply Newton’s third law both to equilibrium situations and to collision interactions and relate it to the conservation of momentum in collisions

Principle of Conservation of Momentum The total momentum before an event (collision or explosion) is equal to the momentum after *Warning* “Total” means if there is more than one object, then you add the momentums of the individual objects together. Set up the air track with a stationary trolley in the middle (that has velcro attached). Knock another (also velcro’d) trolley towards it. Point out that they are assumed to stick together. Ask them to compare the initial velocity with that of both together (much slower in the end) why? The mass has become greater Task: When you have watched the demonstration on the air track, write a small paragraph explaining what you observed

Collisions Always divide the situation into before and after What is the total momentum before the collision? BEFORE 20ms-1 0ms-1 500kg 400kg ? ms-1 Therefore what is the total momentum after the collision? AFTER ? Kg So assuming they stick, what velocity do they travel off at?

Collisions 0ms-1 20ms-1 ? ms-1 ? Kg When solving these, use your estimation skills and common sense. If the two objects collide, then the speed of them when attached together will likely be LESS than the fastest object. BEFORE Momentum before (P(b)) 0ms-1 20ms-1 Object 1: m x v = 10000 kgms-1 Object 2: m x v = 0 kgms-1 Total: 10000 + 0 = 10000kgms-1 500kg 400kg AFTER Momentum before (P(b)) = Momentum after(P(a)) ? ms-1 ? Kg So momentum of both objects together must equal 10000kgms-1 Total mass is now 900kg p= m x v 10000kgms-1 = 900kg x v v= 10000/900 = 11.1ms-1

Draw diagrams with before and after to help! Collision practice… A 0.5 kg trolley is pushed at a velocity of 1.2ms-1 into a stationary trolley B of mass 1.5 kg. The two trolleys stick to each other after the impact. Calculate the velocity they travel at. A 1000 kg rail wagon moving at a velocity of 5.0ms-1 on a level track collides with a 2ms-1 1500 kg wagon. The two wagons move together after the collision. Calculate the velocity they travel at. Draw diagrams with before and after to help! 0.3ms-1, 3.2ms-1, Try them out!

- Collisions: Head on! 20ms-1 12ms-1 ? ms-1 Always make the forward (to the right) direction positive! - BEFORE 20ms-1 12ms-1 500kg 400kg What information is missing from the velocity of the blue car? AFTER ? ms-1 ? Kg Using the same approach, what is their velocity together?

- Collisions: Head on 20ms-1 12ms-1 ? ms-1 ? Kg BEFORE Momentum before (P(b)) Object 1: m x v = 10000 kgms-1 Object 2: m x v = -4800 kgms-1 Total: 10000 + (-4800) = 5200kgms-1 500kg 400kg AFTER Momentum before (P(b)) = Momentum after(P(a)) ? ms-1 So momentum of both objects together must equal 5200kgms-1 Total mass is now 900kg p= m x v 5200kgms-1 = 900kg x v v= 5200/900 = 5.78 ms-1 ? Kg FORWARD

Draw diagrams with before and after to help! Collision practice… A car of mass 1000 kg travels east at 30ms-1 and collides with a 3000kg truck traveling west at 20ms-1. What velocity do they have assuming they stick? Draw diagrams with before and after to help! 0.3ms-1, 3.2ms-1, Try them out!

Watch this video and then explain the following… Engage Watch this video and then explain the following… Why does the gun recoil?

What is the total momentum before? Explosions! BAM KAPOW BOOOOM 0ms-1 BEFORE What is the total momentum before? Gun: 1.2kg Bullet: 0.005kg 400ms-1 AFTER 1.7ms-1 (bullet has p of 2kgms-1) Momentum before (P(b)) = Momentum after(P(a)) So momentum of both objects together must equal 0kgms-1

Explosions! BAM KAPOW BOOOOM https://www.youtube.com/watch?v=8c3aHHG7_Q0 Explosions! BAM KAPOW BOOOOM ? Kg 0ms-1 BEFORE Momentum before (P(b)) Object 1 + 2: m x v = 1.205kg x 0 Gun: 1.2kg Bullet: 0.005kg Total = 0kgms-1 400ms-1 AFTER 500kg Task: If the bullet is speeding off, how is momentum conserved? Which law supports this?

Complete the Following Evaluate Complete the Following

Securing (4-6) Describe examples of momentum in collisions Learning Objectives Developing (3) Define momentum, recall and use the equation (momentum = mass x velocity) Securing (4-6) Describe examples of momentum in collisions Exceeding (7-9) Apply Newton’s third law both to equilibrium situations and to collision interactions and relate it to the conservation of momentum in collisions