## Friday, November 1, 2013

### Day 2 Rocket Model building

Day 2 Rocket Model building https://sites.google.com/a/moe.edu.sg/rocketbuilding/homework/lesson2
http://tinyurl.com/hgssrocket

some activities for model building

Task 1: the real rocket should stop when it hits the ground. make simulation pause
 if ( y<0 font=""> _pause(); }

Task 2: make rocket rotate at the top of the motion
 if (vy>0){ rotate = 0; } else if (vy<0 font=""> rotate = pi; }
hint: you need to declare the variable rotate in the Variables page.

 goto View and add a slider called mFuel and has the values as shown in the picture

 goto View and add a slider called m and has the values as shown in the picture

 goto View and add a field called m and has the values as shown in the picture

Task 5: is gravity constant as the rocket moves up to outer-space?
here, physics is important to implement the appropriate solution to work out the gravity at height y, based on the knowledge that gravity on Earth's surface is about 9.81 m/s^2
// because g = G Mearth /r^2
//therefore the ratio
// g/gs = 1/( y+Rearth)^2 / 1/Rearth^2

g = gs*Rearth*Rearth/( (y+Rearth)*(y+Rearth) );
 goto fixed relationship to add g = gs*Rearth*Rearth/( (y+Rearth)*(y+Rearth) ); to calculate the gravity at height y as experienced by the rocket's position.
hint: remember to declare all variables you come up with like Rearth initial value is 6.37E6 metre, gs initial value is 9.81 m/s^2, g gravity at the height y.
 Rearth initial value is 6.37E6 or 6.37x10^6 metre where E stands for exponential like x10^6
add a bar to display the value of g so that you can make sense if the calculation is correctly executed.

Task 6: model the temperature of air as y increases.
// formula given is T = T0 − L*y
// where T0 = Temperatureo = 288 K is the temperature at sea level
//where L is the “temperature lapse rate” (L = 0.0065 Kelvin per meter).
// when y reach what height it will be zero K ?
// in real life, 0 K cannot be reached in outer-space, it is about a bit higher say, 0.0065 K

can you design your logic codes to be something like this?
 if (y<44307 br=""> Temperature= Temperatureo- L*y;}else if (y>44307){ Temperature=0.0065;}

if (y<44307 br="">
Temperature= Temperatureo- L*y;
}
else if (y>44307){
Temperature=0.0065;
}

more to come!

photo gallery