Wnich statement best describes the purpose of Earth's spheres? They work together as open systems to cycle matter through ecosystems.
They work independently as closed systems to cycle matter through ecosystems.
They work together as open systems to move matter to living and nonliving parts of Earth.
- They work independently as closed systems to move nutrients to living and nonliving parts of Earth.

Identify the type of energy used in each action. the flexing of an arm muscle: a signal transduction process by a neuron: a ball at the top of a hill: 1. electrical energy 2. mechanical energy 3. gravitational potential energy

What best describes the dropping height of a ball that bounces back up to a height of 45 cm

In 2015, about ten percent of total u.s. energy consumption was from renewable energy sources. renewable energy plays an important role in reducing greenhouse gas emissions. when renewable energy sources are used, the demand for fossil fuels is reduced. sanjay and his family want to cut back on their use of non-renewable resources at home. they are thinking of an alternate way to heat their home without adding more greenhouse gases or pollutants to the environment. which renewable resource would not fit into their plan? a) solar power b) burning wood c) constructing a wind turbine eliminate d) generating hydroelectric power