During a workout, a person repeatedly lifts a 13 lb barbell through a distance of 1.5 ft. How many "reps" of this lift are required to burn off 100 Cal?
thanks a bunch!
Well, burning calories is no joke! Let's do some clown math to find out. One rep of lifting a 13 lb barbell through a distance of 1.5 ft would require doing some work, but let's convert everything to the metric system because, why not?
We have 13 lbs, which is approximately 5.9 kilograms (rounded to one decimal place), and 1.5 ft, which is approximately 0.46 meters (rounded to two decimal places).
Now, let's calculate the work done in lifting the barbell. The work done (W) is equal to the force (F) multiplied by the distance (d). In this case, W = F × d.
The force is equal to the weight, which is the mass (m) multiplied by the acceleration due to gravity (g). In this case, F = m × g.
If we assume the acceleration due to gravity is approximately 9.8 m/s², we can calculate the force. F = 5.9 kg × 9.8 m/s².
Now, we have the force and the distance, so we can calculate the work done. W = (5.9 kg × 9.8 m/s²) × 0.46 m.
By multiplying these values together, we find that one repetition of the lift requires approximately 26.44 joules of work.
Now, let's convert calories to joules. One calorie is approximately 4.184 joules. So, 100 calories would be approximately 418.4 joules.
If we divide the work required per repetition (26.44 joules) into the total work needed to burn off 100 calories (418.4 joules), we find that approximately 15.82 reps are required.
So, it looks like you'll need to do approximately 15.82 reps of lifting that barbell to burn off those 100 calories. Time to get to work and lift those weights, clown-style!
To determine the number of "reps" required to burn off 100 calories during a workout, we need to consider the amount of work done (calories burned) during each repetition.
The amount of work done is equal to the force exerted multiplied by the distance covered. In this case, the force exerted is the weight of the barbell, which is 13 lbs, and the distance covered is 1.5 ft.
First, we need to convert the weight of the barbell to kilograms, as calories are usually measured using the metric system. Since 1 lb is approximately 0.45 kg, the weight of the barbell is approximately 5.9 kg.
Next, we convert the distance covered during each repetition from feet to meters. As 1 ft is approximately 0.3 meters, the distance is approximately 0.45 meters.
Now, we can calculate the work done during each repetition using the formula:
Work = Force x Distance
Work = 5.9 kg x 0.45 meters
Work ≈ 2.66 Joules
To convert this work into calories, we can use the conversion factor of 1 calorie ≈ 4.18 Joules.
Calories ≈ Work / 4.18
Calories ≈ 2.66 / 4.18
Calories ≈ 0.64
Therefore, each repetition burns approximately 0.64 calories.
To find the number of reps required to burn off 100 calories, we divide 100 by 0.64:
Number of reps = 100 / 0.64
Number of reps ≈ 156.25
Therefore, approximately 156 repetitions of lifting the 13 lb barbell through a distance of 1.5 ft are required to burn off 100 calories during a workout.
This problem is more complicated than it looks, because the body is nowhere near 100% efficient in doing work. The actual work involved each time the barbell is lifted is 13 x 1.5 = 19.5 ft lb.
19.5 ft lb = 6.43 gram-calories = 0.00643 "food" Calories
100 Calories of actual work would be performed after 100/.00643 = 15,550 lifts, but 100 Calories of food energy would be burned long before that