A garage door is mounted on an overhead rail (Fig. P11.79). 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 0.52. 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 950 N. It is pushed to the left at constant speed by a horizontal force F → . (a) If the distance h is 1.60 m. what is the vertical component of the force exerted on each wheel by the track? (b) Find the maximum value h can have without causing one wheel to leave the track.
A garage door is mounted on an overhead rail (Fig. P11.79). 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 0.52. 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 950 N. It is pushed to the left at constant speed by a horizontal force F → . (a) If the distance h is 1.60 m. what is the vertical component of the force exerted on each wheel by the track? (b) Find the maximum value h can have without causing one wheel to leave the track.
A garage door is mounted on an overhead rail (Fig. P11.79). 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 0.52. 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 950 N. It is pushed to the left at constant speed by a horizontal force
F
→
. (a) If the distance h is 1.60 m. what is the vertical component of the force exerted on each wheel by the track? (b) Find the maximum value h can have without causing one wheel to leave the track.
John is pushing his daughter Rachel in a wheelbarrow when it is stopped by a brick 8.00 cm high (see the figure below). The
handles make an angle of 0 = 15.5° with the ground. Due to the weight of Rachel and the wheelbarrow, a downward force
of 382 N is exerted at the center of the wheel, which has a radius of 15.0 cm. Assume the brick remains fixed and does not
slide along the ground. Also assume the force applied by John is directed exactly toward the center of the wheel. (Choose
the positive x-axis to be pointing to the right.)
(a) What force (in N) must John apply along the handles to just start the wheel over the brick?
N
(b) What is the force (magnitude in kN and direction in degrees clockwise from the -x-axis) that the brick exerts on
the wheel just as the wheel begins to lift over the brick?
magnitude
KN
direction
clockwise from the -x-axis
John is pushing his daughter Rachel in a wheelbarrow when it is stopped by a brick 8.00 cm high (see the figure below). The handles make an angle of 0 = 20.0° with the ground. Due to the weight of
Rachel and the wheelbarrow, a downward force of 407 N is exerted at the center of the wheel, which has a radius of 18.0 cm. Assume the brick remains fixed and does not slide along the ground. Also
assume the force applied by John is directed exactly toward the center of the wheel. (Choose the positive x-axis to be pointing to the right.)
&
(a) What force (in N) must John apply along the handles to just start the wheel over the brick?
1690.53
X
Your response differs from the correct answer by more than 10%. Double check your calculations. N
(b) What is the force (magnitude in kN and direction in degrees clockwise from the -x-axis) that the brick exerts on the wheel just as the wheel begins to lift over the brick?
magnitude
KN
direction
° clockwise from the -x-axis
A uniform ladder 12 meters long rests against a vertical frictionless wall, as shown in the figure. The ladder weighs 400 N and makes an angle θ = 51° with the floor. A man weighing 874 N climbs slowly up the ladder. When he is 7.8 m from the bottom of the ladder, it just starts to slip. What is the coefficient of static friction between the floor and the ladder?
Chapter 11 Solutions
University Physics with Modern Physics (14th Edition)
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