In a science lab, a teacher instructed students to attach a piece of very fine steel wool to a clamp stand inside a fume hood. The students then lit a burner placed under the steel wool. The metal strands began to glow bright red and flames filled the steel wool. After the burner was turned off, the metal continued to burn, leaving behind reddish-brown strands that collapsed into a powder when it was touched after cooling. Based on these observations, did the steel wool undergo a chemical change or a physical change? Explain your answer.

16. a brave but inadequate rugby player is being pushed backward by an opposing player who is exerting a force of 800 n on him. the mass of the losing player plus equipment is 90.0 kg, and he is accelerating at 1.20m/s2 size 12{1 "." "20"" m/s" rsup { size 8{2} } } {} backward. (a) what is the force of friction between the losing player’s feet and the grass? (b) what force does the winning player exert on the ground to move forward if his mass plus equipment is 110 kg? (c) draw a sketch of the situation showing the system of interest used to solve each part. for this situation, draw a free-body diagram and write the net force equation.