C is not mechanical weathering. It is chemical weathering.
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Answer:g=9.79
,A object of mass

at the surface of earth experiences a force

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Explanation:
Let
be the mass of earth.
Let
be the radius of earth.
Let
be the universal gravitational constant.
Given,




Let
be the acceleration due to gravity.
Then,


A object of mass
at the surface of earth experiences a force 
Answer:
Step 7- Communicate. Present/share your results. Replicate.
Step 1- Question.
Step 2-Research.
Step 3-Hypothesis.
Step 4-Experiment.
Step 5-Observations.
Step 6-Results/Conclusion
Explanation: