A weightlifter raises a barbell of mass 150 kg from the floor to over his head 2.5 meters in 3 seconds. What is his average power input?
To calculate the average power input of the weightlifter, we can use the formula:
Average Power = Work ÷ Time
To find the work done, we can use the formula:
Work = Force × Distance
In this case, the force applied by the weightlifter is equal to the weight of the barbell, which can be calculated using the formula:
Weight = Mass × Acceleration due to gravity
Acceleration due to gravity is approximately 9.8 m/s².
Let's calculate step-by-step:
1. Calculate the weight of the barbell:
Weight = Mass × Acceleration due to gravity
Weight = 150 kg × 9.8 m/s²
Weight = 1470 N
2. Calculate the work done:
Work = Force × Distance
Work = Weight × Distance
Work = 1470 N × 2.5 m
Work = 3675 J
3. Calculate the average power input:
Average Power = Work ÷ Time
Average Power = 3675 J ÷ 3 s
Average Power ≈ 1225 W
Therefore, the weightlifter's average power input is approximately 1225 Watts.
To calculate the average power input of the weightlifter, we can use the formula:
Average Power = Work / Time
First, let's find the work done by the weightlifter. The work done is equal to the force applied multiplied by the distance moved:
Work = Force × Distance
The force applied can be calculated using Newton's second law of motion:
Force = mass × acceleration
In this case, the mass of the barbell is given as 150 kg, and we need to find the acceleration. Since the barbell is being lifted upward against gravity, the acceleration is equal to the acceleration due to gravity (9.8 m/s²), but in the opposite direction:
Acceleration = -9.8 m/s²
Next, we need to calculate the distance moved by the barbell. The barbell is raised 2.5 meters above the ground, so the distance moved is 2.5 meters.
Now, we can calculate the force and the work:
Force = mass × acceleration = 150 kg × (-9.8 m/s²)
Work = Force × Distance = (150 kg × (-9.8 m/s²)) × 2.5 meters
Finally, we can calculate the average power input:
Average Power = Work / Time = (150 kg × (-9.8 m/s²) × 2.5 meters) / 3 seconds
By substituting the given values into the formula, we can find the average power input of the weightlifter.
m * g * h / t
150 * 9.8 * 2.5 / 3 = ? Watts