Least count of a stop watch is 0.2 sec. the time of 20 oscillations of a pendulum is measured to be 25 sec. the max % error in measurement is:

An insulated 40 ft^3 rigid tank contains air at 50 psia and 120°f. a valve connected to the tank is now opened, and air is allowed to escape until the pressure inside drops to 25 psia. the air temperature during this process is kept constant by an electric resistance heater placed in the tank. determine the electrical work done during this process.

The force it would take to accelerate an 900-kg car at the rate of 6m/s2

What is the name of the perceived change in a sound wave’s frequency due to motion between the observer and the sound source?