4.- The piston of a hydraulic car jack has a diameter of 32 cm. Calculate the pressure needed to lift a car weighing 1000 kg.
NB. Do the exercise in your notebook. To see the solutions drag the mouse over the "solutions" control. Drag the mouse over the drawing. Calculate the value of the pressure using the computer's calculator and compare your calculations with the ones you see when you click on the "answer" control.