if the zero level is a distance 2h/3 above the floor what is the potential energy U of the block on the floor?

To calculate the potential energy of the block on the floor, we need the mass of the block and the gravitational constant. Assuming the block has a mass "m" and the gravitational constant is "g", the potential energy "U" can be calculated using the formula:

U = m * g * h

Where:
U is the potential energy
m is the mass of the block
g is the gravitational constant (approximately 9.8 m/s^2)
h is the height above the reference level

In this case, the reference level is the floor. Given that the zero level is a distance 2h/3 above the floor, we can substitute 2h/3 for the height "h" in the formula.

Therefore, the potential energy on the floor can be expressed as:

U = m * g * (2h/3)

Remember to substitute the appropriate values for the mass of the block and the gravitational constant to get the final numerical answer.