Gymnasts often practice on foam floors, which increase the collision time when a gymnast falls. what effect does this have on collisions? the change in momentum needed to stop the gymnast is increased. the change in momentum needed to stop the gymnast is decreased. the force exerted by the floor on the gymnast decreases. the force exerted by the floor on the gymnast increases.

The force exerted by the floor on the gymnast decreases.  

Explanation:

Gymnasts practice on foam floors. This reduces their injury. If a gymnast falls, the collision time increases. Since the change in momentum is constant, the impulse would be constant. For change in momentum to remain constant, the force exerted by the floor would decrease.

Impulse, I = f × t = Δp = constant.

Thus, as the time of the collision increases, the gymnasts have less impact.

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step 1 ammonium can be absorbed by plants, but some is converted into nitrates which are better for plants to absorb. this is called nitrification. 2. step 2 the deer eats the plants and uses the nitrogen-containing proteins for cell growth. 3. step 3 bacteria in the soil conduct nitrogen fixation to convert nitrogen gas from the atmosphere into ammonium. 4. step 4 some of the nitrates are absorbed back into plants, but denitrification breaks down the nitrates into nitrogen gas released back into the atmosphere. 5. step 5 nitrogen is found in the urine, which gets broken down into ammonium through the process of ammonification. 6. step 6 plants absorb the ammonium and begin assimilation, the process to add the nitrogen to protein.