A weightlifter lifts a 275 kg barbell from the ground to a height of 2.4 m. How much work has the weightlifter done in lifting the barbel and how much work is required to hold a weight at that height?
Correct answer: C. 6468J and 0J respectively
- A. 3234J and 0J respectively
- B. 3234J and 3234J respectively
- C. 6468J and 0J respectively
- D. 6468J and 6468J respectively
Explanation
To calculate the work done in lifting the barbell, use the formula Work = Force x Distance. The force required is equal to the weight of the barbell, which is mass times the acceleration due to gravity (9.8 m/s²). Thus, Force = 275 kg x 9.8 m/s² = 2695 N. The work done is then Work = 2695 N x 2.4 m = 6468 J. Once the barbell is lifted, holding it at that height requires no additional work because there is no displacement. Therefore, the correct answer is 6468J and 0J respectively. Options A and B miscalculate the work done to lift the barbell, while Option D incorrectly states that work is required to hold the barbell at a height.
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