A world record was set for the men’s 100-m dash in the 2008 Olympic Games in Beijing by Usain Bolt of Jamaica. Bolt "coasted" across the finish line with a time of 9.69 s. If we assume that Bolt accelerated for 3.00 s to reach his maximum speed, and maintained that speed for the rest of the race, (a) calculate his maximum speed and (b) his acceleration

Respuesta :

Answer:

Vmax = 12.21m/s

[tex]a = 4.07m/s^{2}[/tex]

Explanation:

For the first 3 seconds:

[tex]V_{3}=V_{o}+a*t=0+a*3=3a[/tex]   This is the maximum speed. But we need acceleration.

[tex]X_{3}=V_{o}*t+\frac{a*t^{2}}{2} =\frac{9*a}{2}[/tex]

For the other 6.69s with constant speed:

[tex]X_{t}=100=X_{3}+V_{3}*t[/tex]

[tex]100=\frac{9*a}{2} +3*a*6.69[/tex]   Solving for a:

[tex]a = 4.07m/s^{2}[/tex]  Now we replace this value on [tex]V_{3}=3a[/tex]:

[tex]V_{3}=V_{max}=12.21m/s[/tex]