Adog whistle uses a frequency higher than humans can normally hear. a pet owner wants to test his dog whistle. the owner has a drive a car and blow the whistle while he stands on the sidewalk. in which direction should the driver drive so that the pet owner can hear it and why? a) the driver should drive away from the pet owner to use the doppler effect. b) the driver should drive toward the pet owner to make the frequency lower. c) the driver should drive away from the pet owner to change the speed of sound. d) the driver should drive away from the pet owner to use make the frequency higher.

Three different objects, all with different masses, are initially at rest at the bottom of a set of steps. each step is of uniform height . the mass of each object is a multiple of the base mass : object 1 has mass 4..00m , object 2 has mass 1..96m , and object 3 has mass . when the objects are at the bottom of the steps, define the total gravitational potential energy of the three-object system to be zero. if the objects are then relocated as shown, what is the new total potential energy of the system? each answer requires the numerical coefficient to an algebraic expression. each algebraic expression is given using some combination of the variables , , and , where is the acceleration due to gravity. enter only the numerical coefficient. (example: if the answer is 1..23mgd , just enter 1.23)

Consider a system with two masses that are moving away from each other. why will the kinetic energy differ if the frame of reference is a stationary observer or one of the masses?

Which of the following is not a physical property of mattera. melting pointb. heat of combustionc. viscosityd. boiling point