1. Explain why sportsmen use shoes with spikes.
  
a. Sporting individuals wear  shoes to boost traction on surfaces.
  
b. Spikes in the shoes  friction.
  
2. Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?
  
a. A heavier object creates  friction.
  
b. Seema has to exert  force.