. A weightlifter lifts a 76.0 kg barbell 2.60 m 20 times in 1.50 minutes. What is his power output
(a) in watts and (b) in hp?
a. Fb = m*g = 76 * 9.8 = 744.8 N. = Force of barbell.
Po = 20 * 744.8 * 2.6/90s = 430.3 J/s =
430.3 W.
b. hp = 430.3/746 = 0.577
To calculate the power output of the weightlifter, we first need to understand the formula for power. Power is defined as the rate at which work is done or the rate at which energy is transferred or transformed.
The formula for power is given by:
Power = Work / Time
In this scenario, the work done by the weightlifter can be calculated using the formula:
Work = Force x Distance
The force exerted by the weightlifter is equal to the weight of the barbell. The weight is calculated by multiplying the mass of the barbell by the acceleration due to gravity.
Force = Mass x Gravity
Given:
Mass (m) = 76.0 kg
Distance (d) = 2.60 m
Time (t) = 1.50 minutes = 90 seconds
Acceleration due to gravity (g) = 9.8 m/s^2
Let's calculate the power output in watts and in horsepower:
(a) Power output in watts:
1. Calculate the weight (force) of the barbell:
Force = Mass x Gravity
Force = 76.0 kg x 9.8 m/s^2
2. Calculate the work done by the weightlifter:
Work = Force x Distance
Work = (76.0 kg x 9.8 m/s^2) x 2.60 m
3. Calculate the power output:
Power = Work / Time
Power = (76.0 kg x 9.8 m/s^2 x 2.60 m) / 90 seconds
(b) Power output in horsepower:
1 horsepower (hp) is equal to 745.7 watts.
To convert power from watts to horsepower, divide the power in watts by 745.7.
Now you can calculate the power output in watts and in horsepower using the given values.