A child does a 12 j of work pushing his 3kg toy truck with what velocity does the toy move after the child done pushing

We have to assume that the truck was not moving

before he started pushing it.

After he did 12 J of work pushing it, the truck had

12 J of kinetic energy.

Kinetic energy = (1/2) (mass) (speed²)

12 J = (1/2) (3 kg) (speed²)

Divide each side by 1.5 kg : 12J / 1.5 kg = speed²

1 J = 1 newton-meter (12 kg-m²/sec²) / (1.5 kg) = speed²

= 1 kg-m² / sec²

(12 / 1.5) (m²/sec²) = speed²

Speed = √ (8 m²/s²)

Speed = 2.83 m/s.

We can't say anything about velocity, because we don't know

anything about the direction in which the truck is moving.