10m/s - 3m/s = 7m/s
The resultant velocity is 7m/s
1km=1000m=1000000mm
118km/h=118000000 mm/h
Answer:
<em>The sprinter traveled a distance of 7.5 m</em>
Explanation:
<u>Motion With Constant Acceleration
</u>
It's a type of motion in which the rate of change of the velocity of an object is constant.
The equation that rules the change of velocities is:
![v_f=v_o+at\qquad\qquad [1]](https://tex.z-dn.net/?f=v_f%3Dv_o%2Bat%5Cqquad%5Cqquad%20%5B1%5D)
Where:
a = acceleration
vo = initial speed
vf = final speed
t = time
The distance traveled by the object is given by:
![\displaystyle x=v_o.t+\frac{a.t^2}{2}\qquad\qquad [2]](https://tex.z-dn.net/?f=%5Cdisplaystyle%20x%3Dv_o.t%2B%5Cfrac%7Ba.t%5E2%7D%7B2%7D%5Cqquad%5Cqquad%20%5B2%5D)
Using the equation [1] we can solve for a:
![\displaystyle a=\frac{v_f-v_o}{t}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20a%3D%5Cfrac%7Bv_f-v_o%7D%7Bt%7D)
The sprinter travels from rest (vo=0) to vf=7.5 m/s in t=2 s. Computing the acceleration:
![\displaystyle a=\frac{7.5-0}{2}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20a%3D%5Cfrac%7B7.5-0%7D%7B2%7D)
![a=3.75\ m/s^2](https://tex.z-dn.net/?f=a%3D3.75%5C%20m%2Fs%5E2)
Now calculate the distance:
![\displaystyle x=0*2+\frac{3.75*2^2}{2}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20x%3D0%2A2%2B%5Cfrac%7B3.75%2A2%5E2%7D%7B2%7D)
![\displaystyle x=7.5\ m](https://tex.z-dn.net/?f=%5Cdisplaystyle%20x%3D7.5%5C%20m)
The sprinter traveled a distance of 7.5 m
Average speed = (total distance covered) / (total time to cover the distance)
= (2,742 km) / (4.33 hours)
= (2,742 / 4.33) km/hr
= 633 km/hr (rounded)