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On observing a sign board about speed limit, a driver applies brakes and reduces his speed from 100 m/s to 50 m/s though a distance of 50 m. The uniform retardation provided by the brakes (in m/s2) will be ♡ 25♡ 75♡ 50♡ 10 |
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Answer» Explanation:Initial velocity = 100 m/sFinal velocity = 50 m/sDistance travelled = 50 mRetardation➜ Here we have to find the deceleration of the vehicle.➜ By NEWTON's third equation of motion we know that, v² - u² = 2as where V = final velocity U = initial velocity a = acceleration s = DISTANCE travelled➜ Substitute the data, 50² - 100² = 2 × a × 50 100 a = 2500 - 10000 100 a = -7500 a = -7500/100 a = -75➜ Hence the retardation of the vehicle is -75 m/s²➜ Here acceleration is NEGATIVE since it is retardation or deceleration.➜ Hence option B is correct. ➜ The three equations of motion are:v = u + ats = ut + 1/2 × a × t²v² - u² = 2as |
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