T 6.1.2 Exam: Semester Exam Question 21 of 28
How are radar and an approaching siren alike? How are they different?
O A. Both use sound waves, but the Doppler effect can be observed
only in the approaching siren.
O B. Both exhibit the Doppler effect, but radar uses radio, and the siren
uses sound waves.
O C. Both exhibit the Doppler effect, but radar uses sound waves, and
the siren uses radio.
O D. Both use sound waves, but the Doppler effect can be observed
only with radar.
SUBMIT

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.