A double convex lens has faces of radii 18 cm and 20cm. when an object is 24cm the lens,
a real image is formed 32cm from the lens. Determine
1. the focal length of the lens
2. the refractive index of the lens material​

If two metal balls each have a charge of -10^-6 c and the repulsive force between them is 1 n, how far apart are they? (coulomb's constant is k = 9.0x 10^9 n-m^2/c^2? 9.5 m 9.0 mm 9.5 cm 0.9 m .

Amachine, modeled as a simple spring-mass system, oscillates in simple harmonic motion. its acceleration is measured to have an amplitude of 5,000 mm/s with a fre- quency of 10 hz. compute the maximum displacement the machine undergoes during this oscillation.

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?