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प्रश्न
A particle has an initial velocity of `3hat"i" + 4hat"j"` and an acceleration of `0.4hat"i" + 0.3hat"j"`. Its speed after 10 s is ______.
पर्याय
`7sqrt2` units
7 units
8.5 units
10 units
MCQ
रिकाम्या जागा भरा
उत्तर
A particle has an initial velocity of `3hat"i" + 4hat"j"` and an acceleration of `0.4hat"i" + 0.3hat"j"`. Its speed after 10 s is `bb(7sqrt2)` units.
Explanation:
Given `vec"u" = 3hat"t" + 4hat"j", vec"a"= 0.4hat"i" +0.3hat"j"`, t = 10s
From 1st equation of motion.
a = `("v"-"u")/"t"` ∴ v = u + at
⇒ v = `(0.4hat"i" +0.3hat"j")xx10+(3hat"i"+4hat"j")`
⇒ `4hat"i"+3hat"j"+3hat"j"+4hat"j"`
⇒ v = `7hat"i"+7hat"j"`
⇒ `|vec"v"| = sqrt(7^2+7^2)`
= 7`sqrt2` unit.
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