# RE: 400N P3D Rocket

```> whlie looking at the P3D pictures, i noticed the one of dick daniels
> holding the 400 Newton rocket in his hands. it made we wonder
> just how much
> power is 400N. to satisfy my curiosity i'd thought i'd ask so
> here goes:
> between me and my bicycle we weigh 115 Kg. if i were to strap
> on the P3D
> 400N rocket to my bicycle, how long would it take me to
> accelerate from a
> zero to 100 kilometers per hour (assume no friction and a
> level surface)?

Forgot to do the speed check, so here it is. :-)

Mass = 115 kg  (have to assume the rocket motor is included in this figure,
or a way to transfer the force to the bicycle without the motor being on
board is used, to make the problem solveable here - anyone know the mass of
the 400N motor and fuel?)

Assuming no friction or wind resistance (not realistic, but makes it easier
to work out).

Initial speed = 0 km/h (0 m/s)
Final speed = 100 km/h (27.778 m/s)

Firstly, the acceleration - F =ma, so a = f/m, = 400/115, or 3.478 m/s^2
(this is a little over 1/3 G - 1G = 9.81 m/s^2)

v = u + at.  Solving for t, gives t = (v - u)/a

Substituting in the real figures...

t = (27.778 - 0)/3.478

t = 7.986 seconds for 0-100.  In the same ballpark as many cars! :-)

So, P3D's main motor on a bicycle gives sports car like performance on the
straights. :-)
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