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Hello everyone.
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The question here is that a 60 kg sprinter accelerates from rest to the velocity 11 meter per second in time equals to 4 .2 seconds.
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And this is the whole information given here and the first part of the question.
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It is asked that what is the mechanical work done by the sprinter in this time period? mechanical work done.
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So we know that the work done is nothing but force into displacement.
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We know that we can find any work done by multiplying force into the displacement.
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So for finding the force we must know the acceleration here because force equals to ma and we know the mass of the body mass of the printer so we must find the acceleration here.
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So the formula for acceleration is final velocity minus initial velocity by time taken so we must put in the final velocity which is 11 initial velocity is 0 by time taken is 4 .2 seconds so the acceleration is 11 by 4 .2 which is approximately 2 .61 meter per second square this is the acceleration acceleration of this sprinter so now we can find the force which the printer which the sprinter is moving so we can calculate the force by multiplying mass into acceleration.
01:42
So we will get the mass as, we know the mass as 60kg multiplied by 2 .61 equals to 157 .14 newton.
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This is the force with which the printer is moving.
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So we know the force.
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And now we have to find the work done.
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We must know the displacement of the total displacement in time equals to 4.
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2 second.
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So you now must now find the displacement.
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So the formula for displacement is ut plus half 80 square where u is the initial speed t is the time and a is the acceleration.
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So we must put in the values u is zero so this term would get cancelled out.
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The remaining term is half acceleration we know as 2 .61 multiplied by the time which is 4 .2 square if we calculate it carefully, then the value of displacement would be 23 .02 meter.
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So now we have a displacement and we have the force.
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So now we can easily calculate the mechanical work which is w equals to force multiplied by the displacement s, which is 157 .14 multiplied by 23 .02.
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So the value of work done would be 3 ,617 .39.
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This is the value is the answer of part a now in part b we have to calculate the average power so we know that power equals to work done divided by time total work done sorry this is p power power is equal to work done divided by time so we know the value of work done and we know the time total time taken so part b here will calculate it as we know the work done was 3617 .39 3617 .39 jules divided by the time taken was 4 .2 seconds.
03:52
So the answer is 861 .28 watt.
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The unit of power is watt...