How to spawn falling sand with Motion using a spawner minecart

I was trying to make a spawner minecart fountain for like 3 hours and couldn’t find anything that helped me on Google.

With the /summon command, the Minecart could spawn entities with passengers, entities with so many other NBT types but still cannot spawn with Motion:[0.0,1.0,0.0].

This was my command:

/summon spawner_minecart ~ ~1 ~ {SpawnCount:1s,SpawnPotentials:[{Weight:1, Entity: {id: "minecraft:falling_block",DropItem:0b,Motion:[0.0,1.0,0.0],Time:1b}}],SpawnRange:2s,Delay:5s,MaxSpawnDelay:5s,MinSpawnDelay:4s,MaxNearbyEntities:3s,SpawnData:{id:falling_block,Time:1b,Motion:[0.0,1.0,0.0],DropItem:0b},RequiredPlayerRange: 10}

It spawns sand blocks that just fall right down. Is there any way I can fix this?