4.
sarah is a track athlete who is tracking her workouts to improve her speed at the 400m dash. currently, she
is running the 400m in 50s. what is her current speed over this distance?

The current speed of Sarah is 8 m/s.

Explanation:

Speed:

''It is the distance travel in per unit time". It tells the capacity of moving object how fast it is moving.

Unit:

The system international unit of speed is m/s. It can also be given in Km/h

Formula:

r = d / t

r = speed   (it can also be represented by v)

t = time taken to cover the distance

d =  distance

Given data:

Distance = 400 m

Time = 50 s

Speed = ?

Solution:

v = d/ t

v = 400m / 50 s

v = 8 m/s

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml

the answer is b. dilution