JEE Mains · Physics · STD 11 - Newtons laws of motion
- JEE Mains 2021
- Medium
- Numerical
A body of mass \(2\, kg\) moves under a force of \((2 \hat{ i }+3 \hat{ j }+5 \hat{ k }) \,N\). It starts from rest and was at the origin initially. After \(4 \,s\), its new coordinates are \((8, b, 20)\). The value of \(b\) is ........ . (Round off to the Nearest Integer)
Pick an option to check your answer.
Answer & Solution
Correct Answer
(C) \(12\)
Step-by-step Solution
Detailed explanation
\(\overrightarrow{ a } =\frac{\overrightarrow{ F }}{ m }=\frac{2 \hat{ i }+3 \hat{ j }+5 \hat{ k }}{2}\)
\(=\hat{ i }+1.5 \hat{ j }+2.5 \hat{ k }\)
\(\vec{r} =\overrightarrow{ u } t +\frac{1}{2} \overrightarrow{ a } t ^{2}\)
\(=0+\frac{1}{2}(\hat{ i }+1.5 \hat{ j }+2.5 \hat{ k })(16)\)
\(=8 \hat{ i }+12 \hat{ j }+20 \hat{ k }\)
\(b=12\)
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