Two fire trucks with sirens speeds towards and away from an observer. which statement is true involving the doppler effect observed by the observer? a) the doppler effect is not observed by the observer b) due to the doppler effect, the fire truck traveling towards the observer is not heard c) the fire truck traveling away from the observer produces a lower than normal apparent siren frequency d) the fire truck traveling towards the observer produces a lower than normal apparent siren frequency

The correct answer is C.

Explanation:

Doppler effect is a  phenomenon in which there is a relative motion between the source and the observer then there will be change in the frequency of the wave.

For example,when the source and the observer are moving each other then the frequency increases in this case. When the source and the observer are moving away from other then the frequency decreases in this case.

In the given problem, two fire trucks with sirens speeds towards and away from an observer. In this case, the fire the fire truck traveling away from the observer produces a lower than normal apparent siren frequency

Therefore, the correct answer is C.

trig 15.3 cos

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.