Which of these attributes is generally attributed to kepler
a).the orbit of mars is an ellipse
b).the earth is round
c).force of gravity between 2 objects decreases with distance
d).planets move in circles

What will a positive and a negative charge do if they are separated from each other?

Africtionless piston-cylinder contains 50 l of saturated liquid r-134a. the piston has a mass and an area resulting in an applied pressure of 500 kpa on the refrigerant. the refrigerant is now heated until its temperature rises to 70∘c. calculate the work (in kj) done during this process.

Adolphin emits ultrasound at 100khz and uses the timing of reflections to determine the position of objects in the water. part a what is the wavelength of this ultrasound? assume that temperature of water is 20 degrees c. answer in cm