Sam has participated in a 100 m race in his school. If he expensed 450 W power in just the first 2 seconds of the race, then calculate his final velocity after 2 seconds.
Mass of Sam = 50 kg

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Solution

Given : Mass of Sam = 50 kg, Initial velocity of Sam = 0 ms $^{- 1}$ , Power expensed by Sam = 450 W, Time interval = 2 seconds

We know that,
Power = Energy expensed / Time interval
=> Energy expensed = Power x Time interval
=> Energy expensed = 450 x 2 = 900 J

Now, Using work energy theorem for Sam,
1/2 mv $^{2}$ - 1/2 mu $^{2}$ = Energy expensed
=> 1/2 x 50 x v $^{2}$ - 1/2 x m x (0) $^{2}$ = 900
=> 25 x v $^{2}$ - 0 = 900
=> v $^{2}$ = 36
=> v = 6 ms $^{- 1}$

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Sam has participated in a 100 m race in his school. If he expensed 450 W power in just the first 2 seconds of the race, then calculate his final velocity after 2 seconds. Mass of Sam = 50 kg

Sam has participated in a 100 m race in his school. If he expensed 450 W power in just the first 2 seconds of the race, then calculate his final velocity after 2 seconds.
Mass of Sam = 50 kg