Afootball of mass 0.38 kg is traveling towards a boy at 2.8ms-1. the boy kicks the ball with a force of 21n, reversing its direction. if the time of imapct between the football and boy’s foot is 250ms. what is the new speed of trhe ball?

Final speed in reverse direction will be 11 m/s

Explanation:

As per impulse momentum theorem we know that

Change in momentum of the object is product of force and time

so we have

now we have

F = 21 N

now we have

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

3. dark matter

empty space could also be a simple vacuum