38. Describe the effect of using more coils of wire in an electromagnet. A. It stops the flow of electricity. B. It lessens force and repels metals. C. It weakens the strength of the magnetic field D. It increases force to the electromagnet and attracts more metals. 39. Which of the following tends to cause physical or mechanical weathering? A. Animal that burrow in the ground B. Roots of plants growing into the cracks in the rocks Water that seeps into the pores and cracks of rocks D. All of the above C. 40. What will happen to a rock when it is exposed to higher temperature? A. It will contract. B. It will expand. C. It will evaporate. D. It will sink. 41. When is wind an agent of soil erosion? A. When it breaks rocks into pieces B. When it stops picking up rocks C. When it blows rock pieces to other places D. When it presses down rocks​