A 5 N force is defined when a mass of 10 kg is accelerated with
- A.5.0 cm/s²
- B.0.5 m/s²
- C.0.5 cm/s²
- D.5.0 m/s²
Correct answer
Explanation
The correct answer is B, 0.5 m/s². By Newton's second law, F = m × a, so a = F ÷ m = 5 N ÷ 10 kg = 0.5 m/s².
One newton is the force that gives a mass of 1 kg an acceleration of 1 m/s². Force and acceleration are directly proportional for a fixed mass, and acceleration is inversely proportional to mass for a fixed force. Here a 10 kg mass needs 10 N for an acceleration of 1 m/s², so half that force, 5 N, gives half the acceleration, 0.5 m/s². Always keep the units in SI (kilograms, metres, seconds) before calculating.
A is wrong because 5.0 cm/s² is 0.05 m/s², which with 10 kg gives only 0.5 N.
C is wrong because 0.5 cm/s² is 0.005 m/s², which gives just 0.05 N.
D is wrong because 5.0 m/s² on 10 kg needs a force of 50 N.
Exam tip: F = ma; 1 N = 1 kg·m/s²; convert cm/s² to m/s² by dividing by 100.
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