Question 3
What force is needed to give a mass of 3 kg an acceleration of 2 m s−2?
The right answer is the one marked above.
6 N. Both the mass and the acceleration are known, so F = ma applies directly:
F = m a = 3 kg × 2 m s−2 = 6 N
1.5 N comes from dividing instead of multiplying (3 ÷ 2); 5 N from adding. Checking the units catches it: kg × m s−2 = N.