[blaze8902]

As Bob Steele hinted, velocity is significantly more important. If your object is moving at 10m/s at weighs 10kg, then your Energy would be (1/2)(10)(10)^2
so, 500.

Double the mass; (1/2)(20)(10)^2
1000.

Double the velocity; (1/2)(10)(20)^2
2000.

Making it twice as heavy makes it hit twice as hard. Making it twice as fast makes it hit four times as hard.

If you're considering hitting the ball with an object in order to impel it, you should focus on making your "Hitting Object" faster, not heavier.