A mobile starts with a speed of 250m / s and begins to decelerate at a rate of 3m / s². How fast is it after 45s?

Question

A mobile starts with a speed of 250m / s and begins to decelerate at a rate of 3m / s². How fast is it after 45s?

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Thu Nguyệt 4 months 2021-08-09T12:08:41+00:00 1 Answers 4 views 0

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    2021-08-09T12:10:40+00:00

     \large{ \underline{ \underline{ \bf{ \purple{Given}}}}}

    • Speed of the mobile = 250 m/s
    • It starts decelerating at a rate of 3 m/s²
    • Time travelled = 45s

     \large{ \underline{ \underline{ \bf{ \green{To \: find}}}}}

    • Velocity of mobile after 45 seconds

     \large{ \underline{ \underline{ \red{ \bf{Now, \: What \: to \: do?}}}}}

    We can solve the above question using the three equations of motion which are:-

    • v = u + at
    • s = ut + 1/2 at²
    • v² = u² + 2as

    So, Here a is acceleration of the body, u is the initial velocity, v is the final velocity, t is the time taken and s is the displacement of the body.

     \large{ \bf{ \underline{ \underline{ \orange{Solution:}}}}}

    We are provided with,

    • u = 250 m/s
    • a = -3 m/s²
    • t = 45 s

    By using 1st equation of motion,

    ⇛ v = u + at

    ⇛ v = 250 + (-3)45

    ⇛ v = 250 – 135 m/s

    ⇛ v = 115 m/s

    Final velocity of mobile = 115 m/s

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