Final answer:
To calculate the work done by the crane on a 450 kg beam lifted 12 m up at constant velocity, we multiply the force (equal to the weight of the beam, 4414.5 N) by the distance (12 m) to get 52974 joules.
Step-by-step explanation:
To calculate the mechanical work done by the crane when it lifts a 450 kg beam 12 m straight up at a constant velocity, we use the formula for work: Work = Force x Distance. Since the beam is lifted at a constant velocity, the force applied by the crane is equal to the gravitational force on the beam, which can be calculated using the formula for weight: Weight = Mass x Gravitational acceleration (g = 9.81 m/s2). Therefore:
- Weight (Force) = 450 kg x 9.81 m/s2 = 4414.5 N
- Distance the beam is lifted = 12 m
The work done is then:
Work = 4414.5 N x 12 m = 52974 J (joules)
Thus, the crane does 52974 joules of work to lift the beam.