Question

A car is retarded by applying brakes at the rate of the 20ms-² .It is finally stopped in 10 sec .find its initial velocity.​

Answer 1

Explanation:

its final velocity is zero itself ........

चाँद को बिठाकर पहरे पर,

तारों को दिया निगरानी का काम,

आई है यह रात सुहानी लेकर आपके लिए,

एक सुनहरा सपना आपकी आँखों के नाम।

Answer 2

Given :-

• acceleration, a = - 20 m/s² (retardation)
• final velocity, v = 0 m/s (stopped)
• time, t = 10 sec

To Find :-

• find initial velocity (u) ?

Solution :-

we know by Newton's first law of motion

$\underline{\boxed{\bold{at = v - u }}}$

$\bold{: \implies - 20 \times 10 = 0 - u } \\ \\ \bold{: \implies \cancel- 200 = \cancel- u} \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ \bold{: \implies u = 200 \: m^{ - 1} } \: \: \: \: \: \: \: \: \: \:$

so, initial velocity of the car is 200 m/s

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Newton's laws of motion :-

1. at = v - u
2. s = ut + 1/2 at²
3. 2as = v² - u²