Fun on Computers

I can not speak highly enough of this simulation http://www.falstad.com/ripple/

Also down load http://audacity.sourceforge.net/download/windows audacity to see and hear your own voice in waves.

This program teaches Waves http://phet.colorado.edu/sims/wave-on-a-string/wave-on-a-string_en.html

High speed camera showing the critical middle bit of a collision where the kinetic energy is stored in the deformed golf ball before it springs away. Note also that the golf ball springs away with near twice the velocity of the golf club

Homework

Do question 25. Jacaranda page 242
Summarize chapter 1

Kinetic energy in Collisions

Home work Q15 and Q19 of text book

Impulse = Ft = mat = m(u-v)/txt= m(u-v) = change in momentum

Impulse has units of Ns and momentum kg.m/s

Collisions

N3 is for systems of 2 or more bodies. F1->2 =-F2->1. The force of object one on two is equal and opposite (vector speak for minus) of object two on one.
A collision is broken into three parts,

1. heading towards each other (N1),
2. touching, scrunching, and restoring (N3) and
3. heading out from each other (N1)

the collision dynamics, or how step 1 leads to step 3 is in the detail of step 2.

TIME - MOMENTUM

In the actual collision the body one and two feel equal but opposite forces for duration of time.

Considering each body (N2) we have F2->1. t = ma1.t for what happens to body 1

and F1->2. t = ma2.t. Use N3 and the formulae v-u =at to derive conservation of momentum (p)

p1= m1.v1. Conservation means momentum before = momentum after.

DISTANCE - Energy

The collision first through a scrunch deformation stage where KE is converted to mechanical deformation. If the mechanical deformation is springy or elastic, the mechanical deformation is PE (potential energy) that then explodes the particles appart. (PE restore KE).

So unlike momentum the direction matters, and the light object travels a greater distance, loosing more and gaining more KE. The maths is tricky so you will only deal with case of objects colliding and sticking together- Completely inellastic collisions.

Homework: Question 10 and 11 page 244 Jacaranda HSC science.

Thursday Lesson

Dr Hill is away today

You are to go to this link and workthrough the worksheet. I will check your books tomorrow.

You are to email me peter.hill26 reporting the progress on your assignment. Due next Tuesday
Remember - Discussion of Newton
-first law objects continuning motion
-Second law bodies decelerating and having forces(spreading the force)
-third law systems transfering momentum, Changing a lethal short impulse (Ft) to a non-lethal force (fT).
Remember - Evidence of the effectiveness of the device. Follow marking guideline.

Homework

Friday Complete question up to question 20 on page 221
Email teacher if there are problems completing.

Newton 1 (N1) in space

Tuesday - Wednesday Prac

Bike accelerates, cruises, breaks

What of Newtons laws applies to each?

N1 - Cruising, things travel in straight lines

N2- Body accelerates due to residual force acting on body

N3- System transferes force/momentum from one body to another

Assume constant acceleration - vxv = 2xaxd

work out the cruise speed

What was the stopping distance or deceleration,

Is skidding or controlled breaking more effective

Conclusion:=?

Monday

Summarize Chapter 10 - Newtons Laws
Complete all question from chapter 9
First 5 Questions from Chapter 10