Which of these choicse sound the most likea theme

Modify the equation fδt=δ (mv) to find the force of friction.

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.

Matter is needed to transfer thermal energy bya. conductionb. convectionc. radiation d. both a & b.