5) The max, height reached by a bike rider is 250m after she reaches top speed and then coasts up a hill. If 255,000J of kinetic energy was lost to friction, what was her initial
speed? The rider and the bike have a combined mass of 250kg.

Ammonia enters the expansion valve of a refrigeration system at a pressure of 10 bar and a temperature of 18oc and exits at 6.0 bar. the refrigerant undergoes a throttling process. determine the temperature, in oc, and the quality of the refrigerant at the exit of the expansion valve.

Ineed the answer to question 1 , i’m desperate

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 ?