1. Find the torque created when a 50g mass is set 25cm from the fulcrum of a hor

Question

1. Find the torque created when a 50g mass is set 25cm from the fulcrum of a horizontal meter stick with the fulcrum at the center of mass like in the lab.

3. 5.0Nm of torque is applied to a long bar, I=6.3kg·m2, pivoted in the center. What angular acceleration is expected if the bar is being accelerated as in the lab? If it starts from rest, how fast is it spinning after 5.0 seconds?

4. Under what conditions can the center of mass of a meter stick create a torque?

5. How much torque is needed to accelerate a playground merry-go-round at .12rad/s2 if the platform has a moment of inertia of 200kg·m2 and there are 3 kids riding it. Fred is 1.0m from the center and his mass is 25kg, Lucy at 32kg is 1.2m from the center and Jake at 45kg is .50m from the center.

Help!!!

Explanation / Answer

1)mass = 50gm=0.05kg

Weight=0.05*9.8=0.49 N

Lever arm=distance from fulcrum=25 cm

Torque=0.49*0.25=0.1225 Nm

3)angular acceleration=torque/mass momemt of inertia=5/6.3=0.794 rad/s^2

Angular speed after 5 seconds=5*0.794=3.97 rad/s

4)if the center of mass doesn't coincide with the fulcrum, then it can create a torque

5)moment of inertia of merry-go-round and 3 kids=

200+(25*1^2)+(32*1.2^2)+(45*0.5^2)=282.33 kg-m^2

Angular acceleration required=0.12 rad/s^2

Torque required=282.33*0.12=33.88 Nm

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