Question

See the graph of v →t of a moving body. Find out velocity of the body after 5 seconds. Vims') 1 6 0 2 (2) 6 m/s (1) - 9 m/s 3) 10 m/s (4) 15 m/s​

Answer 1

$\huge{\mathrm{-9\:ms^{-1}}}$

Explanation :

From given Graph, one can observe the following things

• Initial Velocity ( u ) = 6 m/s
• Final Velocity ( v ) = 0 m/s
• Total Time taken ( t ) = 2 s

Now, here rises a question, What we are supposed to do ( find ) in this Question? (o o?)

In this question,  we have to calculate the following things

• Acceleration ( a, in order to get a component for $\mathrm{v = u + at}$ )
• & then Final Velocity ( v, which is actually our question)

Solution :

$\orange{\mathrm{First,  we \: will \: start \: by \: starting \: calculation \: over \: acceleration}}\\\mathrm{\because \: \: \: \: \: \: \: v = u + at}\\\\\: \: \: \: \: \mathrm{Substituting \: the \:  given \: values, we \: get}\\ \mathrm{0 \: ms^{-1} = 6 \: ms^{-1} + a(2s)}\\\implies \mathrm{2s(a)= -6 \: ms^{-1}}\\\implies \mathrm{a = -3ms^{-2}}$

$\mathrm{\pink{We \: will \: now \: start \: solving \: this \: question \: to \: evaluate \: v \: when, t = 5\:s}}\\\mathrm{\because v = u + at}\\\implies \mathrm{v = 6\: ms^{-1} + ( \: 3ms^{-2}\: )( 5\: s )}\\\implies \mathrm{v = 6 \:ms^{-1} - 15ms^{-1}}\\\implies \boxed{\green{\mathrm{v = -9 \: ms^{-1}}}}$

Here negative symbol indicates that the final velocity, will be in opposite direction, due to negative acceleration

Thanks! $\mathfrak{;)}$

Happy Learning! :D