A24kg child descends a slide 5m high and reaches the bottom with a speed of 2.8m/s. how much thermal energy due to friction was generated in this process?

Why is metal often used for cooking pan?

Africtionless piston-cylinder contains 50 l of saturated liquid r-134a. the piston has a mass and an area resulting in an applied pressure of 500 kpa on the refrigerant. the refrigerant is now heated until its temperature rises to 70∘c. calculate the work (in kj) done during this process.

Explain why electric current cannot exist if a current doesn't have a voltage source.