Two people are moving a heavy desk. One person pulls to the right with a force of 25 Newtons, while the other pushes to the right with a force of 50 Newtons. There is also 20 Newtons of friction pointing to the left. What is the net force on the desk?

Which of the following is considered to be a vector?               a.  temperature    b.  velocity    c.  time    d.  mass

The friction of the water on a boat produces an acceleration of -10. m/s2. if the boat is traveling at 30. m/s and the motor is shut off, how long it take the boat to slow down to 5.0 m/s?

Two kilograms of air within a piston–cylinder assembly executes a carnot power cycle with maximum and minimum temperatures of 800 k and 300 k, respectively. the heat transfer to the air during the isothermal expansion is 60 kj. at the end of the isothermal expansion the volume is 0.4 m3. assume the ideal gas model for the air. determine the thermal efficiency, the volume at the beginning of the isothermal expansion, in m3, and the work during the adiabatic expansion, in kj.