Answer:
Explanation:
Given
-- initial velocity
--- height
Required
Determine the time to hit the ground
This will be solved using the following motion equation.
Where
So, we have:
Subtract 30.2 from both sides
Solve using quadratic formula:
Where
Split the expression
or
or
Time can't be negative; So, we have:
Hence, the time to hit the ground is 1.82 seconds
a) 4.8 m/s² his average acceleration during the first 2.5 s
b) 15 m distance he cover during the first 2.5 seconds.
c) 31 m/s his speed as he finished the race.
<h3>(a) How to calculate the Average Acceleration ?</h3>Average acceleration is calculated by using Newtons first law of motion
v = u + at
where
u is initial velocity
v is final velocity
a is constant acceleration
t is time
Given u = 0m/s , v = 12 m/s and t = 2.5 sec
Therefore average acceleration is given by
a = 4.8 m/sec²
b) Here we will use newtons second law of motion
On substituting value we get
s = 15m
c) Here we will use newtons third law of motion
v² = u² + 2as
Here u = 0 , a = 4.8 m/s² and s = 100 m
Therefore
v² = 960
v = 31 m/s
Disclaimer: the question was given incomplete in the portal. Here is the complete question.
Question: Usain Bolt's 100m sprint Runner set the world record for the100 meter sprint during the 2009World Championships in Berlin with a time of 9.58 s, reaching a top speed of 12 m/s in about 2.5 s.
a. What was his average acceleration during the first 2.5 s?
b. What distance did he cover during the first 2.5 seconds, assuming his acceleration was constant?
c. If he were able to maintain this constant rate of acceleration, what would have been his speed as he finished the race?
Learn more about Newtons law of motion here:
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