Adevice for exercising the upper leg muscle is shown above, together with a schematic representation of an equivalent lever system. calculate the force exerted by the upper leg muscle to lift the mass at a constant speed.

Two point charges are separated by a certain distance. how does the strength of the electric field produced by the first charge, at the position of the second charge, change if the second charge is doubled? a. the field does not change b. the field strength decreases by half. c. the field strength doubles d. the field strength quadruples