The cheetah is considered the fastest running animal in the world. Cheetahs can
ID: 1876867 • Letter: T
Question
The cheetah is considered the fastest running animal in the world. Cheetahs can accelerate to a speed of 21.7 m/s in 2.50 s and can continue to accelerate to reach a top speed of 28.7 m/s. Assume the acceleration is constant until the top speed is reached and is zero thereafter. 1) Express the cheetah's top speed in mi/h. (Express your answer to three significant figures.) 2) Starting from a crouched position, how long does it take a cheetah to reach its top speed? (Express your answer to three significant figures.) 3) How far does it travel in that time? (Express your answer to three significant figures.) 4) If a cheetah sees a rabbit 120 m away, how long will it take to reach the rabbit, assuming the rabbit does not move?(Express your answer to three significant figures.)
Explanation / Answer
(a) As per the conversion standards,
1 mi/h = 0.44704 m/s
or
1 m/s = 2.23696 mi/h
Therefore,
Top speed in mi/h = 28.7 * 2.236936
Top speed = 64.2 mi/h
(b) v = u + at
21.7 = 0 + a*2.50
a = 8.68 m/s2
Now, to reach the top speed,
v = u + at
t = v/a
t = 28.7 / 8.68
t = 3.306 seconds
(c) d = 1/2* vavg * t
d = 0.5 * 28.7 * 3.306
d = 47.44 m
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