[Question #676183]: About Clump's Velocity Initialization

```New question #676183 on Yade:

Hello,

I've just started learning Yade recently. I want to consolidate several balls together and give one of them initial speed, then let it collide with the surface.

However, when I opened the 3D perspective, I found that in the process, the ball did not have any speed. After checking, I think there is something wrong with my fllowing code.

##################################code############################################
#define parameters

damp=0.1
M=1000
velocity=5
anguler=pi/4

rhoSmall=0.5
rhoBig=3

#define the balls

#clump
clumpId=O.bodies.appendClumped([sphereBig,sphereSmall])

#define the area
O.bodies.append(area)

#change the velocity
O.bodies[clumpId[1][0]].state.vel=(0,velocity*cos(anguler),-1*velocity*sin(anguler))

O.engines=[
ForceResetter(),
InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb()]),
InteractionLoop(
[Ig2_Sphere_Sphere_ScGeom(),Ig2_Facet_Sphere_ScGeom()],
[Ip2_FrictMat_FrictMat_FrictPhys()],
[Law2_ScGeom_FrictPhys_CundallStrack()]
),
NewtonIntegrator(gravity=(0,0,-9.81),damping=damp)
]

O.dt=.05*PWaveTimeStep()

##############################end################################################

Can you find out where the error of my code is? I want to tie more balls together in the future, but the experiment of two balls fails. Can someone answer that?

Yingnan

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