What is the main difference between a food chain and a food web A. There is no difference between them
B. The food chain is a part of the food web but with only one producer, primary consumer, and secondary consumers
C. The food web is a part of the diverse food chain
D. The food chain has land animals and the food web has aquatic animals
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Its definitely not A, nor is it D because food webs and food chains can be either land or aquatic animals. i think its B because a food chain goes up and a food web includes more organisms

It depends on the surface of the levels. the rougher the surface, the greater is the frictional force. for rougher surfaces, you would need to exert greater force to move the object. the concept is that, you must overcome the frictional force in order to bring the object into motion. this is the reason why we add lubricants to the joints so they could easily move. this answer was on