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NECO 2023 · Paper 1 · Q37

A body of mass 700 kg moving with a velocity of 36 kmh−136\text{ kmh}^{-1} is made to attain a velocity of 90 kmh−190\text{ kmh}^{-1} in 15.6 s by a force. Calculate the magnitude of the force.

Worked solution (try it first)
  1. Change the speeds to m/s by dividing by 3.6: 36÷3.6=1036 \div 3.6 = 10 and 90÷3.6=2590 \div 3.6 = 25.
  2. The acceleration is a=v−uta = \dfrac{v - u}{t}
    =25−1015.6= \dfrac{25 - 10}{15.6}, which is about 0.9615 m s−20.9615\text{ m s}^{-2}.
  3. By F=maF = ma, F=700×0.9615≈673F = 700 \times 0.9615 \approx 673 N, option B.

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