Final answer:
The force on the pulley when a 20 g mass is added to a 5 g mass holder is calculated as 0.245 N, using the formula T = mg with g = 9.80 m/s².
Step-by-step explanation:
If we add 20 g to a mass holder of 5 g, the force on the pulley is calculated using the formula T = mg, where T represents the tension in the rope, m is the mass (including both the holder and the additional mass), and g is the acceleration due to gravity which is approximately 9.80 m/s².
First, combine the mass of the holder and the additional mass: 5 g + 20 g = 25 g. Since the standard unit of mass in physics is kilograms, convert grams to kilograms by dividing by 1000: 25 g = 0.025 kg.
Now, use the formula T = mg to find the force on the pulley: T = (0.025 kg)(9.80 m/s²) = 0.245 N.