A person's heart does approximately a work of 1.6 J during a beat. How much work does it do during a day? By how much does the temperature of 10 kg of water rise if it absorbs this much of energy?

PLACEHOLDER ANSWER - the question has two answers. Taking a heart rate of 72 beats per minute (the paper does not give one), there are $$72 \times 60 \times 24 = 103680$$ beats a day. The work done is $$1.6 \times 103680 \approx 1.66 \times 10^5\text{ J}$$. This raises the temperature of 10 kg of water by $$\frac{1.66 \times 10^5}{10 \times 4200} \approx 3.9^\circ\text{C}$$.