Search any question & find its solution
Question:
Answered & Verified by Expert
A car of mass $m$ starts from rest and acquires a velocity along east, $\vec{v}=v \hat{i}(v>0)$ in two seconds. Assuming the car moves with uniform acceleration, the force exerted on the car is
Options:
Solution:
2098 Upvotes
Verified Answer
The correct answer is:
$\frac{m v}{2}$ eastward and is due to the friction on the tyres exerted by the road
$\frac{m v}{2}$ eastward and is due to the friction on the tyres exerted by the road
As given that mass of the car $=m$ As car starts from rest, $u=0$ Velocity acquired along east $(\vec{v})=v \hat{i}$ Time $(t)=2 \mathrm{~s}$.
We know that, $v=u+a t$
$$
\begin{aligned}
&\Rightarrow v \hat{i}=0+a \times 2 \\
&\Rightarrow \vec{a}=\frac{v}{2} \hat{i}
\end{aligned}
$$
(Force, by engine is internal force)
$$
\vec{F}=m \vec{a}=\frac{m v}{2} \hat{i}
$$
Hence, force acting on the car is $\frac{m v}{2}$ towards east due to force of friction is $\frac{m v}{2} \hat{i}$ which moves the car in eastward direction. Hence, force by engine is internal force.
We know that, $v=u+a t$
$$
\begin{aligned}
&\Rightarrow v \hat{i}=0+a \times 2 \\
&\Rightarrow \vec{a}=\frac{v}{2} \hat{i}
\end{aligned}
$$
(Force, by engine is internal force)
$$
\vec{F}=m \vec{a}=\frac{m v}{2} \hat{i}
$$
Hence, force acting on the car is $\frac{m v}{2}$ towards east due to force of friction is $\frac{m v}{2} \hat{i}$ which moves the car in eastward direction. Hence, force by engine is internal force.
Looking for more such questions to practice?
Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.