Shinee set up an experiment as shown below.
Shinee used a spring balance to find out the force need to pull a wooden block across 4 different materials, P, Q, R and S. He started off with material P before subsequently replacing it with material, Q, R and S, one at a time.
He then presented his results in the table below:
Shinee wanted to use a suitable material to place the surface of a ramp so that he could load his cartons up to his vehicle more easily as shown below.
Based on his experimental results, which material would Shinee not choose to place on the surface of the ramp?