Which of the following is an example of the Doppler effect? (2 points) A. A water bug on the surface of a pond is producing small ripples in the water. The bug is not moving
B. A police car with its siren on is driving towards you, and you perceive the pitch of the siren to increase.
C. Scientists measure the speed of light and find that it is constant.
D. The gravitational pull of two objects on each other

Acatapult is tested by roman legionnaires. they tabulate the results in a papyrus and 2000 years later the archaeological team reads (distances translated into modern units): range = 0.4 km; angle of launch = π/5 rad; landing height = launch height. what is the initial velocity of launch of the boulders if air resistance is negligible?

Astudent is performing an experiment comparing sound and light waves. the student gathers the following data. what conclusion does the student most likely make based on this data? light waves always travel the same speed; however, the speed of sound is determined by the medium that it travels through. all sound waves always have the same energy, so the temperature of the medium does not affect wave speed. light needs to vibrate particles, so it travels fastest in tightly packed solids, while sound does not need a medium, so it travels fastest in a gas. tightly packed particles in solids slow down the light waves; however, sound waves make particles bounce into each other, so they travel faster in solids.

Explain what will happen if decomposers were apsent from a forest ecoysystem.