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Question: ABCDE is pentagon. Forces acting on a particle are represented in magnitude and direction by \(\ove...

ABCDE is pentagon. Forces acting on a particle are represented in magnitude and direction by

AB,BC,CD,2DE,AD,\overset{\rightarrow}{AB},\overset{\rightarrow}{BC},\overset{\rightarrow}{CD},2\overset{\rightarrow}{DE},\overset{\rightarrow}{AD}, andAE\overset{\rightarrow}{AE}. Their resultant is given by

A

AE\overset{\rightarrow}{AE}

B

2AB2\overset{\rightarrow}{AB}

C

3AE3\overset{\rightarrow}{AE}

D

4AE4\overset{\rightarrow}{AE}

Answer

3AE3\overset{\rightarrow}{AE}

Explanation

Solution

We have, AB+BC+CD+2DE+AD+AE\overset{\rightarrow}{AB} + \overset{\rightarrow}{BC} + \overset{\rightarrow}{CD} + 2\overset{\rightarrow}{DE} + \overset{\rightarrow}{AD} + \overset{\rightarrow}{AE}

=(AB+BC)+(CD+DE)+(AD+DE)+AE\left( \overset{\rightarrow}{AB} + \overset{\rightarrow}{BC} \right) + \left( \overset{\rightarrow}{CD} + \overset{\rightarrow}{DE} \right) + \left( \overset{\rightarrow}{AD} + \overset{\rightarrow}{DE} \right) + \overset{\rightarrow}{AE}

=(AC+CE)+AE+AE\left( \overset{\rightarrow}{AC} + \overset{\rightarrow}{CE} \right) + \overset{\rightarrow}{AE} + \overset{\rightarrow}{AE} =AE+AE+AE=3AE\overset{\rightarrow}{AE} + \overset{\rightarrow}{AE} + \overset{\rightarrow}{AE} = 3\overset{\rightarrow}{AE}.