Why is parabolic shape is important for a concave mirror

A certain string on a piano is tuned to produce middle c (f = 261.63 hz) by carefully adjusting the tension in the string. for a fixed wavelength, what is the frequency when this tension is tripled?

The evaporation temperature of R-410A at 100 psig is аbout:

What is a Light Year?

Wave D has an amplitude of 2 cm, and wave E has an amplitude of 2 cm. The waves are out of phase. Determine the amplitude of resulting wave F

What is the chemical name for vinegar

would the phases of the moon be affected if the moon didn't make one rotation for each revolution of earth?

What kinetic energy has 1 tone car traveling at 15 m/s

Ceres is a dwarf planet located in the main asteroid belt.

Which solid is the best thermal insulator A. brass b. ice C. styrofoam D. copper

When a high-mass star explodes, which of the following is left over in the center? A. Black hole B. Neutron star C. White Dwarf D. either a or b