The steel wire working a signal is 750 m long and 0.5 cm diameter. Assuming a pull on the wire of 1.5 kN, find the movement which must be given to the signal-box end of the wire if
the movement at the signal end is to be 17.5 cm. Take Young’s modulus as 200 GN/m2

The movement of electrons between atoms is called an

Calculate 9 ∙ 10-5 divided by 3 ∙ 10-9. (box after the "10" in answer is for the

Hydroelectricity provides about 7 percent of the electricity generated in the united states. (a) explain how a hydroelectric power plant converts energy stored in water into electricity. (b) identify two factors that determine the amount of electricity that can be generated by an individual hydroelectricity power plant. (c) describe the two main types of land-based hydroelectric power plants. (d) describe two economic advantages and two environmental disadvantages of hydroelectricity.