A 100 watt bulb emits light at p = 1 w light power. What is the power density at a distance of r=0. 1 and 1 m?.

What is the acceleration of a spaceship that is initially at rest and then speeds up to 220 m/s in 20 seconds

Water is siphoned from a large tank and discharges into the atmosphere through a 50-mm diameter tube. the end of the tube is b = 2.1 m below the tank bottom which is a = 7.4 m deep, and viscous effects are negligible. determine the maximum height h over which the water can be siphoned without cavitation occurring. atmospheric pressure is 101.4 kpa, and the water vapor pressure is 1.79 kpa (absolute)

Explain why electric current cannot exist if a current doesn't have a voltage source.