MYP Physics sample question: Speed, acceleration and force

A cyclist accelerates in a straight line from rest to 6.0 m/s in 4.0 s. The cyclist and bicycle have a combined mass of 80 kg.

1. (a)Calculate the acceleration of the cyclist.[2]
   Show the mark scheme for (a)

   • • a = change in velocity ÷ time (1)
   • • a = 6.0 ÷ 4.0 = 1.5 m/s² (1)
2. (b)Calculate the resultant force acting on the cyclist and bicycle.[2]
   Show the mark scheme for (b)

   • • F = ma (1)
   • • F = 80 × 1.5 = 120 N (1)
3. (c)Calculate the distance travelled in the 4.0 s, assuming the acceleration is constant.[2]
   Show the mark scheme for (c)

   • • distance = average speed × time = ½ × (0 + 6.0) × 4.0 (1)
   • • distance = 12 m (1)

Write the equation, substitute with units, then give the answer with units. Each step can earn a mark even if a later number is wrong.