A 1220 kg automobile travels at 75 m/s. what net work would be required to bring it to a stop

W = - 3431250 [N]

Explanation:

In order to solve this problem, we must use the theorem of work and energy conservation. This theorem tells us that the initial mechanical energy of a body plus the work done on this body must be equal to the final mechanical energy of the body. We must remember that the mechanical energy of a body is equal to the sum of kinetic energies plus potential energy plus elastic energy.

In this problem, we only have kinetic energy.

And we have:

m = mass = 1220 [kg]

v = velocity = 75 [m/s]

As the carriage stops the final kinetic energy is zero.

Now replacing:

Note: The negative force means that the force has to be carried out by the carriage. That is, no external force acts on the car to stop it.

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