What is the correct formula to use for this problem? why do you use ΔxΔp= h/2π instead of ΔxΔp=h/4π?

A molecule of roughly spherical shape has a mass of 1.80 × 10-25 kg and a diameter of 0.6 nm. If the uncertainty in the measured position of the molecule is equal to the molecular diameter, what is the minimum uncertainty in the speed of the molecule? (h = 6.626 × 10-34 J ∙ s)

An electric clothes dryer has a resistance of 8 ohms. it draws 30 a of current. what is the voltage, in volts, of the wall outlet that it is plugged into?

1. jay fills a wagon with sand (about 20 kg) and pulls it with a rope 30 m along the beach. he holds the rope 25° above the horizontal. the rope exerts a 20-n tension force on the wagon. how much work does the rope do on the wagon?

An object with initial temperature 130 ∘ f is submerged in large tank of water whose temperature is 50 ∘ f . find a formula for f ( t ) , the temperature of the object after t minutes, if the cooling constant is k = − 0.2 . remember newton's law of cooling (the rate of change of temperature with respect to time is equal to k times the difference between the temperature of the object and the surrounding temperature) ! : )