A dog whistle uses a frequency higher than humans can normally hear. A pet owner wants to test his dog whistle. The owner has a helper drive a car and blows 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? * The driver should drive away from the pet owner to use the Doppler effect.
The driver should drive toward the pet owner to make the frequency lower.
The driver should drive away from the pet owner to change the speed of sound.
The driver should drive away from the pet owner to make the frequency higher.

chemical energy --> gravitational potential energy --> kinetic energy --> elastic potential energy --> gravitational potential energy

explanation:

when emma starts the hike, the chemical energy stored in her body is used to climb up the mountain, and so she gains gravitational potential energy (because at the end, she will be at a higher height h above the ground). then she goes bungee jumping: as she falls, this gravitational potential energy is converted into kinetic energy (because her speed increases as she falls down), until the point when the rope stretches, and she stops moving. at that moment, all the kinetic energy is converted into elastic potential energy due to the stretching of the rope. then, this energy is released because the rope returns to its natural length, and emma gains a small increase in altitude , so she gains some gravitational potential energy.