Which elements do hydrogen fuel cells combine to produce electricity? hydrogen and oxygen hydrogen and carbon hydrogen, oxygen, and nitrogen hydrogen, carbon, and nitrogen

Which of the statements about waves is true? a. in longitudinal waves, particles move perpendicular to the direction the wave is traveling. b. both transverse and longitudinal waves can travel through water c. electromagnetic waves are a type of longitudinal waves. d. in a transverse wave, particles move parallel to the direction the wave is traveling.

Awind turbine is initially spinning at a constant angular speed. as the wind's strength gradually increases, the turbine experiences a constant angular acceleration 0.173 rad/s2. after making 2870 revolutions, its angular speed is 132 rad/s. (a) what is the initial angular velocity of the turbine? (b) how much time elapses while the turbine is speeding up?

Assume similar data for the motion of the blood in your aorta. estimate how many beats of the heart it will take the blood to get from your heart to your brain. (assume that the distance from your heart to your brain is 30 cm)