Which of the following is an example of the doppler effect? (2 points)
a ocean waves from two different directions that have canceled each other out
b scientists show that different colored lights have different wavelengths
c the movement of objects due to unbalanced forces
d a train blows its horn as it travels towards you, and you perceive the pitch of the horn to increase

10 points! will mark brainiest! in a heat engine if 1,000 j of heat enters the system and the piston does 500 j of work, what is the final internal energy of the system if the initial energy was 2,000 j 1: write the equation2: list out your known variables 3: plug the numbers into the equations 4: solve 5: write your solution statement that includes initial energy and final energy added you so much!