When you see a traffic light turn red, you apply the brakes and stop with constant acceleration. if your initial speed was 23 m/s , what is your average speed during braking? express your answer to two significant figures and include the appropriate units.

Let the initial velocity be u = 23 m/s

Let the final velocity be v.

Vehicle stops finally, therefore v = 0 m/s

Here during the braking, vehicle decelerates with constant acceleration,  thus the change in velocity is linear from initial velocity to final velocity.

for the Given condition:

Write the expression for the average speed

Substitute the values in the above expression.

Hence, the average speed during braking is 11.5 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

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement