Question

A body of mass $2kg$ is moving in straight line for which $v-x$ graph is shown in the figure. Magnitude of force acting on the body at $x=10m$ is $5kN$. Find the value of $k$.

Answer 1

We know,

$|F|=m|a|$ given m=2kg.

And,

$|a|=|v\frac{dv}{dx}|$

From the graph,

$\frac{dv}{dx}=-1$

And, $v_{atx=10}=10m/s$

$|a{|}_{atx=10}=10$

$F=10\times 2=20N$

According to question,

$F=5k$

Hence $k=4$.