What is commonly used to run a central heating system?

Plzz worth 10 ! which statement about energy transformations is not true? a all forms of energy can be transformed into thermal b energy is never destroyed or created during transformations c potential chemical energy always transforms into kinetic d some thermal energy is always released during a transformation

Do you agree with scientist’s prediction about the warming of alaska and other polar regions?

Three different objects, all with different masses, are initially at rest at the bottom of a set of steps. each step is of uniform height . the mass of each object is a multiple of the base mass : object 1 has mass 4..00m , object 2 has mass 1..96m , and object 3 has mass . when the objects are at the bottom of the steps, define the total gravitational potential energy of the three-object system to be zero. if the objects are then relocated as shown, what is the new total potential energy of the system? each answer requires the numerical coefficient to an algebraic expression. each algebraic expression is given using some combination of the variables , , and , where is the acceleration due to gravity. enter only the numerical coefficient. (example: if the answer is 1..23mgd , just enter 1.23)