Askier (68kg) starts from rest but then begins to move downhill with a net force of 92 n for 8.2 s. the hell levels out for 3.5 seconds. on this part of the hill, the net force on the skier is 22 n backwards.
(a) calculate the speed of the skier after 8.2 s
(b) calculate the speed of the skier at the end of the section where the hill levels out
(c) calculate the total distance travelled by the skier before coming to rest

(a) 11.1 m/s

The acceleration of the skier is given by:

where F = 92 N is the net force and m = 68 kg. Substituting,

After 8.2 s, the speed of the skier is

where

a = 1.35 m/s^2 is the acceleration

t = 8.2 s is the time

Substituting,

(b) 10.0 m/s

In this section of the hill, the net force is F = -22 N backwards. So, the acceleration of the skier is

When starting this section, the skier is moving at u = 11.1 m/s. So, the final speed will be:

And substituting t=3.5 s, we find

(c) 237.9 m

The distance travelled by the skier in the downhill section is

where a = 1.35 m/s^2 and t = 8.2 s. Substituting,

The distance travelled by the skier in the levelled out section is given by

where

v = 0 is the final speed

u = 11.1 m/s is the initial speed

a = -0.32 m/s^2 is the acceleration

d is the distance

Solving for d,

So, the total distance is

d = 45.4 m + 192.5 m = 237.9 m

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

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