You are looking at satellite data for a cloud. It reflects about 30% of the light that hits it, and has a brightness temperature of 270 K. The surface surrounding the cloud appears to have a brightness temperature of 295 K. What would be a good estimate for the temperature of the cloud

Your target variable is δf, the magnitude of the difference in frequency between the waves emitted from the sonar device and the waves received by the device after reflecting off the whale. write an expression for δf in terms of the relevant frequencies using the subscript notation introduced above.

It is really hard for me right know

Suppose that three astronomical objects, 1, 2, and 3 are observed to lie on a line, and the distance from object 1 to object 3 is d. object 1 has four times the mass of object 3, and seven times the mass of object 2. find the distance between objects 1 and 2 for which the net force on object 2 is zero.