Accepted Answer
That's very interesting. I come up with the same digits as you do, but my decimal point is in a different place. So, as far as you went, you did a lot of things right.Also, notice that the question wants the weight in Newtons, but you've expressed your answer in kg. That's a mass,not a weight.Since I can't look over your work, I can't show you where your mistake is. I guess that means that I have to go all through it . . . I have to show you mine without ever seeing yours, and when I'm done, I get 5 points. I am truly psyched for the challenge !The shaft is a long steel cylinder.The volume of a cylinder is V = π (radius)² (length)Diameter = 35 mm = 0.035 meterRadius = 17.5 mm = 0.0175 meterLength = 675mm = 0.675 meterVolume = π (0.0175)² (0.675) cubic meters(about 0.00065 m³)Mass = (Volume) x (density) = ( π x (0.0175)² x 0.675 x 7,680 ) kilograms(about 4.987 kg)Weight = (mass) x (gravity) = ( π x (0.0175)² x 0.675 x 7,680 ) x (9.81) = about 48.93 Newtons. (almost exactly 11 pounds) If you used ' 10 ' for the acceleration of gravity,then the weight would be about 49.87 Newtons.If you stopped at mass (kg) then you're off by a factor of 100 .If you used the mass to find the weight, then you're off by a factor of 10 .
Related Question in Physics
