The moment of a 40g mass hanging from a 55 cm pivot point is calculated using the formula moment = force × distance, giving an answer of approximately 0.22 Nm.
The student has asked how to calculate the moment of a 40g mass hanging from a meter rule that balances at a point 55 cm from one end. To find the moment, we can use the formula: moment = force × distance from pivot. The force exerted by the mass is equal to its weight, to convert grams to kilograms we have 40g which is equivalent to 0.040 kg. We use the acceleration due to gravity (9.81 m/s²) to find the force in newtons (N), which is
0.040 kg × 9.81 m/s² = 0.3924 N. Note that the distance from the pivot must be in meters, hence 55 cm is converted to 0.55 m. Therefore, the moment is 0.3924 N × 0.55 m = 0.21582 Nm, which is approximately 0.22 Nm.
So, the correct answer is D. 0.22 Nm.