A dragster starts from rest and accelerates at 26.0 m/s^2 for 5.56 s. How far does it travel in this time?
A145 m
B402 m
C289 m
D804 m
Answer & Solution
Correct answer: B. 402 m
1. Identify the knowns: the initial velocity is 0, the acceleration is 26.0 m/s^2 and the time is 5.56 s.
2. Use position equals initial position plus initial velocity times time plus half the acceleration times time squared.
3. Both the initial position and the initial velocity are zero, so this reduces to half the acceleration times time squared.
4. Substitute the values: 0.5 x (26.0 m/s^2) x (5.56 s)^2.
5. Since (5.56 s)^2 = 30.9 s^2, the displacement is 0.5 x 26.0 x 30.9 = 402 m.
6. Leaving out the factor of one half gives 804 m, exactly double the right answer.
_Source: OpenStax College Physics (CC BY 4.0), Ch 2 "Kinematics", section 2.5 Motion Equations for Constant Acceleration in One Dimension_
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