Studying for physics test in a week need help with torque?

[匿名]

2016-03-02 7:12 pm

1) A 3.2 kg flagpole extends from a wall at an angle of 25◦
from the horizontal. Its center of gravity (center of mass
in this case) is 1.6 m from the point where the pole is attached to the wall. What is the gravitational torque on the
flagpole about the point of attachment?

the next question is not related

2) A 1.0 m long dumbbell has a 10 kg mass on the left and a 5.0 kg mass on the right. Find the position of the center
of gravity and the torque due to gravity on the dumbbell.

回答 (2)

Amy

2016-03-02 7:43 pm

✔ 最佳答案

Torque is F x R, where F is the force, R is the distance from pivot to force, and x means vector multiplication.
The magnitude of FxR is FRsin(a), where a is the angle between F and R.

Gravity is vertical, so it makes a 65 degree angle with a bar that is 25 degrees from horizontal.
Force of gravity is mass * g.

torque = (3.2 kg)(9.81 m/s/s)(1.6 m)(sin(65 degrees))

Center of gravity is the position where the total torque due to gravity is zero, because the torques in each direction have equal magnitude. If this center is a distance x from the left end of the dumbbell, then:
(10 kg)(g)(x) = (5 kg)(g)(1 m - x)
x = 1/3 m

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[匿名]

2016-03-02 7:12 pm

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