This is a suggested answer to the GCE O Level Pure Physics examination, year 2019, Paper 1, multiple choice question 8.

The question provided the following data on a car that is accelerating

  • Mass of car is 800kg
  • The car’s engine exerts a driving force of 2500N
  • Acceleration of car is 2.0m/s2

The student is required to calculate the resistive force acting on the car.

Suggested Solution:

The answer is A. That is, the resistive force is 900N.

Explanation:

The Resultant force  that resulted in the car accelerating is given by the formula:

Resultant Force, F = Mass x acceleration

           F = 800kg x 2.0m/s2

    = 1600N

The Resultant force is actually the result of the force the car engine exerts (which is given as 2500N) and the resistive force.

Hence, the Resistive Force = 2500N-1600N

=900N