A 120-MT concrete beam is lifted from the floor by two tandem heavy lift cranes up to a target height of 7.5 meters.

Calculate the potential energy of the beam when it is at 7.5 meters.

The potential energy of an object is given by the equation:

Potential Energy = mass * gravity * height

where mass is the mass of the object (in this case, the concrete beam), gravity is the acceleration due to gravity (approximately 9.8 m/s^2), and height is the distance above a reference point (in this case, the floor) at which the object is located.

Given:
Mass of the concrete beam = 120 MT (or 120,000 kg)
Height = 7.5 m

Potential Energy = 120,000 kg * 9.8 m/s^2 * 7.5 m
= 8,820,000 kg·m^2/s^2

Therefore, the potential energy of the beam at 7.5 meters is 8,820,000 kg·m^2/s^2.

To calculate the potential energy of the beam when it is at a height of 7.5 meters, you need to know the mass and gravitational acceleration.

Given:
Mass of the beam (m) = 120 metric tons = 120,000 kg
Height (h) = 7.5 meters
Gravitational acceleration (g) = 9.8 m/s^2 (approximate value)

The formula to calculate potential energy (PE) is:
PE = m * g * h

Substituting the values:
PE = 120,000 kg * 9.8 m/s^2 * 7.5 meters

Calculating:
PE = 8,820,000 joules

Therefore, the potential energy of the concrete beam when it is at a height of 7.5 meters is 8,820,000 joules.