Final answer:
The estimated average force on the blood as it moves through the baby's heart is calculated using Newton's second law, resulting in a force of 0.02 N which is option A.
Step-by-step explanation:
To estimate the average force on the 20 g of blood as it moves through the baby's heart, we need to use the principle of Newton's second law, which states that force is equal to the mass times the acceleration (F = ma). However, since the blood enters and leaves the heart at different speeds, we firstly need to calculate the acceleration using the change in velocity over time.
Given that the blood enters the heart at 25 cm/s and leaves at 35 cm/s, we have a change in velocity (Δv) of 35 cm/s - 25 cm/s = 10 cm/s. The time interval (Δt) during which this change occurs is 0.10 seconds. First, we convert the mass of the blood from grams to kilograms (20 g = 0.02 kg) because the standard unit of mass in the SI system is the kilogram.
Acceleration (a) can be found using the formula Δv/Δt = 10 cm/s / 0.10 s = 100 cm/s². Since 1 m = 100 cm, we convert this to meters per second squared: 100 cm/s² = 1 m/s². Now, applying Newton's second law, we calculate the force (F):
F = ma = 0.02 kg × 1 m/s² = 0.02 N.
Therefore, the estimated average force on the blood is 0.02 N, which corresponds to option A.