the surface tension of water in contact with air at 20c is given as 0.0716 n/m. the pressure inside a droplet of water is to be 0.0147 n/cm2 greater than the outside pressure, calculate the diameter of the droplets of water ?

An engineer, who is designing a water toy, is making preliminary calculations.  A user of the product will apply a force F1 that moves a piston (D = 80 mm)  at a speed of Vpiston = 300 mm/s. Water at 15 oC jets out of a converging nozzle  of diameter d = 15 mm. To hold the toy stationary, the user applies a force F2  to the handle. Calculate F2. Neglect friction between the piston and the walls. Calculate F1. Neglect friction between the piston and the walls.

*A person holds her hand out of an open car window while the car drives through still air at 65 mph. Under standard atmospheric conditions, what is the maximum pressure on her hand? What would be the maximum pressure if the car were an Indy 500 race car traveling at 200 mph?

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