A 500 Kg crate is carried horizontally at a constant speed of 7m/s. What is the Kinetic energy of the crate?

The kinetic energy of the crate, K.E.
= (1/2) m v²
= (1/2) × 500 × 7² J
= 12300 J

As the crate is at a constant speed, the acceleration, a = 0
The force acting on the crate, F = m a = 0
The work done on the crate, W = F s = 0

The momentum of the crate, p
= m v
= 500 × 7 kg•m/s
= 3500 kg•m/s

The work done would be 0 if the crate was put down again.
Carried at a constant speed, no KE is generated. Only if it is accelerated.
It will have some momentum.