In an experiment 4.5 kg of a fuel was completely burnt. The heat produced was measured to be 180,000 kJ. Calculate the calorific value of the fuel.

Two bodies whose masses are m_1 = 50 kg and m_2 150g are tight by a string and placed in a horizontal surface. When m_1 is pulled by a force F and acceleration of 5ms^-2 is produced in both the bodies. Calculate the value of F and tension in the strong.

Calculate the amount of heat produced when 2kg substance pulled in a floor with a velocity 2m/s in 5 sec.