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Question

A particle starting from rest moves in a straight line such that after time, I (seconds), the acceleration becomes $(6 - t / 4) cm / (s ^ 2)$ When the acceleration becomes zero, the velocity of the particle in cm/s is _______(round off to 1 decimal place).

Particle Motion: Finding Velocity from Acceleration

The problem asks for the velocity of a particle at the specific instant when its acceleration becomes zero. We are given the initial condition that the particle starts from rest.

1. Define Acceleration and Initial Conditions

  • Acceleration $a(t)$ is given by: $a(t) = (6 - t/4) \text{ cm/s}^2$.
  • The particle starts from rest, meaning its initial velocity $v(0) = 0$.

2. Find Time When Acceleration is Zero

Set the acceleration function to zero and solve for time ($t$):

$a(t) = 0$ $6 - \frac{t}{4} = 0$ $6 = \frac{t}{4}$ $t = 6 \times 4 = 24$ seconds.

The acceleration becomes zero after 24 seconds.

3. Determine Velocity Function using Integration

Velocity $v(t)$ is the integral of acceleration $a(t)$ with respect to time:

$v(t) = \int a(t) dt = \int (6 - \frac{t}{4}) dt$ $v(t) = 6t - \frac{t^2}{4 \times 2} + C$ $v(t) = 6t - \frac{t^2}{8} + C$

Use the initial condition $v(0) = 0$ to find the constant $C$:

$0 = 6(0) - \frac{0^2}{8} + C$ $C = 0$

Therefore, the velocity function is:

$v(t) = 6t - \frac{t^2}{8}$

4. Calculate Velocity at $t = 24$s

Substitute $t = 24$ seconds into the velocity function:

$v(24) = 6(24) - \frac{(24)^2}{8}$ $v(24) = 144 - \frac{576}{8}$ $v(24) = 144 - 72$ $v(24) = 72 \text{ cm/s}$

5. Round Off the Result

Rounding the velocity to one decimal place gives $72.0$ cm/s.

The calculated velocity $72.0$ cm/s falls within the range specified by the correct answer (71 to 73).

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Important Questions from Indefinite Integrals

  1. What is \(U(x)\,V(x)\) equal to?
  2. $X^4 + C$ is the general integral of

  3. What is \(\rm \int \frac{dx}{x(x^2 + 1)}\)  equal to?

  4. If \(\rm \int \sqrt{1 - sin 2x} \space dx\)  = A sinx + B cosx + C, where 0 < x <  \(\frac{\pi}{4}\) , then which one of the following is correct?

  5. What is \(\smallint {{\rm{e}}^{\sin {\rm{x}}}}\left( {\frac{{{\rm{x}}{{\cos }^3}{\rm{x}} - \sin {\rm{x}}}}{{{{\cos }^2}{\rm{x}}}}} \right){\rm{dx}}\) equal to?

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