A pendulum clock is taken to the moon (g = 1.6 N/kg). How long must the pendulum be in order for the clock to continue keeping accurate time (1 second cycle)?
3.2 m
7.9 m
0 0.25 m
0.041 m

Anybody wanna ? (picture included? )

With the simplified model of the eye, what corrective lens (specified by focal length as measured in air) would be needed to enable a person underwater to focus an infinitely distant object? (be careful-the focal length of a lens underwater is not the same as in air! assume that the corrective lens has a refractive index of 1.62 and that the lens is used in eyeglasses, not goggles, so there is water on both sides of the lens. assume that the eyeglasses are 1.90

A100-watt light bulb illuminates a solar cell. the electricity from the solar cell operates a water pump that delivers 1 watt of power. what is the efficiency of the system?