A garage door is mounted on an overhead rail (the figure (Figure 1) ). The wheel

Question

A garage door is mounted on an overhead rail (the figure (Figure 1) ). The wheels at A and B have rusted so that they do not roll, but rather slide along the track. The coefficient of kinetic friction is 0.55. The distance between the wheels is 2.00 m, and each is 0.50 m from the vertical sides of the door. The door is uniform and weighs 855 N . It is pushed to the left at constant speed by a horizontal force F .

Part A

If the distance h is 1.63 m , what is the vertical component of the force exerted on the wheel A by the track?

If the distance h is 1.63 m , what is the vertical component of the force exerted on the wheel B by the track?

Part C

Find the maximum value h can have without causing one wheel to leave the track.

Explanation / Answer

F = 0.5 mg = 0.5 ( 855) = 427.5 N

net torque is zero

Fh + A( 2.0 m) = 855 ( 1)

427.5 N ( 1.63) + A ( 2) = 855

A = 79.08 N

(b)

weight is eqal to total vertial force

Fb = 855-79.08 N =775.9125 N

(c)

force at point A to be zero net torque of force and weight is equl to zero

F h = 855 (1)

427.5 * h = 855

h = 2 m

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