A dragster starts from rest, accelerates at 26.0 m/s^2 and covers 402 m. What is its final velocity, worked out without using the time?
A209 m/s
B104 m/s
C145 m/s
D290 m/s
Answer & Solution
Correct answer: C. 145 m/s
1. Identify the knowns: the initial velocity is 0, the acceleration is 26.0 m/s^2 and the displacement is 402 m.
2. Choose the equation that links velocity, acceleration and displacement without time.
3. The final velocity squared equals the initial velocity squared plus twice the acceleration times the displacement.
4. Substitute the values: 0 + 2 x (26.0 m/s^2) x (402 m).
5. This gives a velocity squared of 2.09 x 10^4 m^2/s^2.
6. Take the square root: the final velocity is 145 m/s.
7. Quoting 209 m/s reports the intermediate square without taking the root.
_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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