A resultant force of magnitude 15N acts on a body of mass 250g. Calculate the magnitude of the acceleration

Analyze the question: A resultant force of 15 N acts on a body of mass 250 g. We need the acceleration.

Concept: Newton's Second Law states F = ma, so a = F/m.

The mass must be in kilograms (SI units) so that the force in newtons gives acceleration in ms⁻².

Solution:

1. Convert the mass: 250 g = 250 ÷ 1000 = 0.25 kg
2. Apply the formula:

a = F/m = 15 / 0.25 = 60 ms⁻²

Check against the options: 60.

Common mistakes:

• Using 250 directly without converting grams to kg gives 15/250 = 0.06 ms⁻² (option A, a trap).
• Multiplying instead of dividing gives 15 × 0.25 = 3.75 (option B, another trap).

Tip: Always convert to SI units first (g → kg, cm → m) before using any formula. Dividing by 0.25 is the same as multiplying by 4, so 15 × 4 = 60 quickly.