The security alarm on a parked car goes off and produces a frequency of 813 hz. the speed of sound is 343 m/s. as you drive toward this parked car, pass it, and drive away, you observe the frequency to change by 72.1 hz. at what speed are you driving?

You are driving at Vo= 15.2 m/s = 54.72 km/h

Explanation:

Δf= 72.1 Hz

f= 813 Hz

v= 343 m/s

Δf= f* [ (v-(-vo) / v) - ( v-(vo) / v) ]

clearing vo:

Vo= 15.2 m/s

given data:

determine the horse power (h.p) = ?

force applied to move the box(f) = 10 pounds,

box lifted from a distance         (d) = 3 feet

time taken to lift                         (t) = 10 sec,

the horse power is defined as amount of work required to move a load. the horse power is equal to 550 foot-pound per second

                  1 h.p   = 550 foot-pound/second

it can also be defined as the the load that need to be move a body for certain distance in a certain amount of time.

mathematically,

                      h.p = (force × distance)/ time

                            = (10 × 3)/ 10

                            = 30/10

                            = 3 foot -pound/sec

hence, the horse power is needed to move the box is 3 foot-pound/second

important note: 1 h.p = 550 foot-pound/second = 746 watts

a.

explanation: