ommon Take TutonalAssignment aspx Student: ddIO008gauburnedu My Accou Class Mana
ID: 3163884 • Letter: O
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ommon Take TutonalAssignment aspx Student: ddIO008gauburnedu My Accou Class Management Torque; Moment of Inertia: Rotational Dynamics Begin Date: 3 62017 1 00 AM ue Date 0173.00.00 PM End Date: 12 00:00 AM Problem You've been gaven the challenge of balancing a uniform, rigid memer-stick with mass M gon a pivot Stacked on the 0 em end of the meter stuck identical coins, each wth mass m 45g, so that the center of mass of the coins is directly over the end of the meter stack The pivot point will be measured from the 0-cm end of the meter stick. 25% Part (a) Determine the distance d. in am if there is n, 1 coun on the end of the meter stick, and the system is to remain in static Grade Summary a 15 Part (b Determine the distance d. (in cm) if there are n coins on the end of the mener would have to stack at the 0.em mark if the distance was less than number of coins you 25 Part (e) What is the minamum Round to the nearest whole in equilibrium ifd-o? a 25 Part (do Is it possible no Mack enough coins to keep itExplanation / Answer
According to the given problem,
Total mass = 99.5 gm and this is supported by the pivot at da from the coins.
The centre of gravity of the ruler acts down at 50 cm from the coins.
The coins themselves are at zero from the coins.
a) The moments must add to zero.
so 99.5 * da - 95 * 50 + 4.5 * 0 = 0
da = 95*50 / 99.5 = 47.74cm
b) 4 coins mass = 113
so 113 * db - 95 * 50 + 18 * 0 = 0
db = 42.035 cm
c) As we know where the pivot is we might choose to calculate moments from this point.
The coins are 10.01 and the centre of mass is 39.99 cm from the pivot.
n* 4.5 * 10.01 - 95 * 39.99 + F * 0= 0
n = 95* 39.99 / ( 4.5 * 10.01 )-> 84 coins.
We don't use the force up on the pivot (F) because that is a distance of zero from the pivot and cannot contribute to the torque measured around this point.
You pick points, any points, to avoid having to include unknowns in the expression for torque.
d) No, there is no force to balance the torque.
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