a weigh lifter raises a 70-kg barbell from the floor to a height of 2.2 m in 1.2s what was his average power output during the lift?
work = m g h = 70 * 9.81 * 2.2 joules
power = work in Joules /time in seconds
= 70 * 9.81 * 2.2 / 1.2
in Joules per second which is WATTS
To calculate the average power output, we need to use the formula:
Power = Work / Time
First, let's calculate the work done by the weight lifter. The work done is equal to the force applied multiplied by the distance traveled.
Work = Force * Distance
The force applied can be calculated using Newton's second law of motion:
Force = Mass * Acceleration
Since the barbell is not accelerating vertically (moving at a constant speed), the upward force applied must equal the downward force of gravity. Therefore, the force applied is equal to the weight of the barbell.
Weight = Mass * Gravity
Now, we can calculate the work done:
Work = Force * Distance
= Weight * Distance
Next, we need to calculate the distance traveled. The weight lifter raises the barbell to a height of 2.2 m. Therefore, the distance traveled is 2.2 m.
Finally, we can substitute the values into the formula for work and calculate the average power output:
Power = Work / Time
Let's calculate step by step:
1. Calculate the force applied:
Weight = Mass * Gravity = 70 kg * 9.8 m/s² = 686 N
2. Calculate the work done:
Work = Force * Distance = 686 N * 2.2 m = 1509.2 J (Joules)
3. Calculate the average power output:
Power = Work / Time = 1509.2 J / 1.2 s = 1257 watts or 1.26 kilowatts
Therefore, the average power output during the lift is 1257 watts or 1.26 kilowatts.