A Thomson’s gazelle can run at very high speeds, but its acceleration is relatively modest. A reasonable model for the sprint of a gazelle assumes an acceleration of 4.2m/s2 for 6.5s , after which the gazelle CONTINUES at a steady speed.
a. What is the gazelles top speed?
b. A human would win a very short race with a gazelle. The best time for a 30 m sprint for a human runner is 3.6 s. How much time would the gazelle take for a 30 m race?
Answer:
The correct answer will be:
(a) 27.3 m/s
(b) 3.8 s
Explanation:
According to the question:
Acceleration,
[tex]a= 4.2 \ m/s^2[/tex]
Time,
[tex]t = 6.5 \ s[/tex]
(a)
The gazelles top speed will be:
⇒ [tex]V_{max} = at[/tex]
[tex]=4.2\times 6.5[/tex]
[tex]=27.3 \ m/s[/tex]
or,
[tex]= 27 \ m/s[/tex]
(b)
As we know,
s = 30 m
Now,
⇒ [tex]s = \frac{1}{2} at^2[/tex]
or,
⇒ [tex]t=\sqrt{\frac{2s}{a} }[/tex]
On putting the given values, we get
[tex]=\sqrt{\frac{2\times 30}{4.2} }[/tex]
[tex]=\sqrt{\frac{60}{4.2} }[/tex]
[tex]=3.78 \ s[/tex]
or,
[tex]=3.8 \ s[/tex]