The \(x\) and \(y\) coordinates of the particle at any time are \(x = 5t-2t^2\) and \(y=10t\) respectively, where \(x\) and \(y\) are in metres and \(t\) is in seconds. The acceleration of the particle at \(t=2\) s is:
1. \(0\) m/s2
2. \(5\) m/s2
3. \(-4\) m/s2
4. \(-8\) m/s2

Subtopic:  Acceleration |
 84%
Level 1: 80%+
NEET - 2017
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The position vector of a particle changes with time according to the relation,
\(\vec{r}(t)=(15 t^2) \hat{i}+\left(4-20 t^2\right) \hat{j},\) where \(\vec{r}(t)\) is in metres and \(t\) is in seconds.
What is the magnitude of the acceleration at \(t=1\) second?  
1. \(100\) m/s2 2. \(40\) m/s2
3. \(50\) m/s2 4. \(25\) m/s2
Subtopic:  Acceleration |
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Level 1: 80%+
JEE
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At time \(t=0,\) a particle starts travelling from a height of \(7\hat z\) cm in a plane, keeping the \(\mathrm{z}\)-coordinate constant. At any instant of time, its position along the \(x\text-\) and \(y\text-\)directions is defined as \(3t\) and \(5t^{3}\) respectively. At \(t=1 \) s, the acceleration of the particle is:
1. \(-30\hat{y} \) 2. \(30\hat{y}\)
3. \(3\hat{x} +15\hat{y} \) 4. \(3\hat{x} + 15\hat{y} + 7\hat{z}\)
Subtopic:  Acceleration |
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Level 2: 60%+
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Which of the following motions of an object always results in zero acceleration?
1. Any motion in a straight line.
2. Projectile motion.
3. Any motion in a circle.
4. None of the motions above guarantees zero acceleration.
Subtopic:  Acceleration |
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Level 2: 60%+
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