Easy MCQ +4 / -1 PYQ · JEE Mains 2023

The distance travelled by an object in time $t$ is given by $s=(2.5) t^{2}$. The instantaneous speed of the object at $\mathrm{t}=5 \mathrm{~s}$ will be:

  1. A $5 \mathrm{~ms}^{-1}$
  2. B $12.5 \mathrm{~ms}^{-1}$
  3. C $62.5 \mathrm{~ms}^{-1}$
  4. D $25 \mathrm{~ms}^{-1}$ Correct answer

Solution

The distance traveled by an object in time $t$ is given by the equation $s = (2.5)t^2$. To find the instantaneous speed at a specific time, we need to find the first derivative of the distance function with respect to time, which gives us the velocity function: <br/><br/> $v(t) = \frac{ds}{dt}$ <br/><br/> Differentiating the given equation with respect to $t$: <br/><br/> $v(t) = \frac{d}{dt} (2.5)t^2 = 2(2.5)t = 5t$ <br/><br/> Now, we can find the instantaneous speed at $t = 5 \mathrm{~s}$ by plugging the value into the velocity function: <br/><br/> $v(5) = 5(5) = 25 \mathrm{~m/s}$ <br/><br/> The instantaneous speed of the object at $t = 5 \mathrm{~s}$ is $25 \mathrm{~m/s}$.

About this question

Subject: Physics · Chapter: Kinematics · Topic: Motion in a Straight Line

This question is part of PrepWiser's free JEE Main question bank. 112 more solved questions on Kinematics are available — start with the harder ones if your accuracy is >70%.

Drill 25 more like these. Every day. Free.

PrepWiser turns these solved questions into a daily practice loop. Chapter-wise drills, full mocks, AI doubt chat. No auto-renew.

Start free →