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Ch 02: Kinematics in One Dimension
Knight Calc - Physics for Scientists and Engineers 5th Edition
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Not the one you use?Change textbook
Chapter 2, Problem 36b

The position of a particle is given by the function x = (2t3 - 6t2 + 12) m, where t is in s. At what time is the acceleration zero?

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Step 1: Start by recalling that acceleration is the second derivative of the position function with respect to time. The position function is given as x(t) = 2t^3 - 6t^2 + 12.
Step 2: Compute the first derivative of the position function to find the velocity function. Use the power rule for differentiation: v(t) = dx/dt = d/dt(2t^3 - 6t^2 + 12).
Step 3: Differentiate the velocity function to find the acceleration function. Again, use the power rule: a(t) = dv/dt = d/dt(6t^2 - 12t).
Step 4: Set the acceleration function equal to zero to find the time when the acceleration is zero. Solve the equation a(t) = 0 for t.
Step 5: Solve the resulting equation for t, ensuring you check for all possible solutions. These values of t represent the times when the acceleration is zero.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Position Function

The position function describes the location of a particle as a function of time. In this case, the position x is given by the polynomial equation x = 2t^3 - 6t^2 + 12, which indicates how the particle's position changes over time. Understanding this function is crucial for determining the particle's velocity and acceleration.
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Velocity

Velocity is the rate of change of position with respect to time, mathematically represented as the first derivative of the position function. For the given position function, the velocity v can be found by differentiating x with respect to t. This step is essential for analyzing the motion of the particle and determining when the acceleration is zero.
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Acceleration

Acceleration is the rate of change of velocity with respect to time, represented as the second derivative of the position function. To find when the acceleration is zero, one must differentiate the velocity function obtained from the position function and set it equal to zero. This indicates points in time where the particle is not changing its velocity, which is critical for understanding its motion.
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