Final answer:
The resisting force in mass wasting, such as the force a dam must withstand, is determined by friction and inertia, but notably smaller than the total weight of the material involved. It depends on factors like the water's depth and the dam's dimensions.
Step-by-step explanation:
The resisting force in mass wasting is largely attributed to friction. In the context of a dam holding back water, this force is far smaller compared to the overall weight of the water behind the dam. In the example provided, while the weight of the water in the reservoir is 1.96 × 10¹³ N, the actual force exerted on the dam is only a fraction of this.
Inertia is another form of resistance in physical systems, reflecting an object's resistance to changes in its velocity. However, when considering the force a dam must withstand, it is essential to understand that the actual force is influenced by water's average depth and the dimensions of the dam rather than the mass of water itself.
The thickness of a dam often increases with depth to counteract the increasing force due to water pressure, which is dependent on depth. Despite the large forces involved, the dam does not need to counteract the entire weight of the water, but rather the water pressure exerted at a certain depth.