Free-body diagrams for four situations are shown below. For each situation, determine the net force acting upon and the direction of the force vector.

What is the weight of a feather (mass = 0.0001 kg) that floats through earth's and the moon's atmospheres?

Consider a 1000 w iron whose base plate is made of 0.5 cm thick aluminum alloy 2024-t6 (ρ = 2770 kg/m3 and cp = 875 j/kg°c). the base plate has a surface area of 0.03 m2. initially, the iron is in thermal equilibrium with the ambient air at 22°c. assuming 90% of the heat generated in the resistance wires is transferred to the plate, determine the minimum time needed for the plate temperature to reach 200°c.

The ph is the a. independent variable b. the dependent variable c. control group