Hey guys. So I am currently studying for an AP Physics exam. I don't understand how to calculate c) d) and e). I'd appreciate some help. I need it fast!

In which of the following is positive work done by a person on a suitcase

The diagram shows a boulder rolling down a hill into a valley and then up the opposite hill. at which position does the boulder have the greatest kinetic energy? ab c d

1700 j of energy is lost from 0.14 kg object , the temperature decreases from 50°c to 45°c what is the specific heat of this object, amd what is the material ?