As shown in the figure, the mass of object a close to the vertical side is Ma = 0.2kg, and the mass of object B on the horizontal plane is MB = 1kg, As shown in the figure, the mass of the object a on the vertical side is Ma = 0.2kg, and the mass of the object B on the horizontal plane is MB = 1kg. The weight of the rope and the friction between the rope and the pulley are not included. The OB part of the rope is horizontal, and the OA part is vertical. A and B just move at a constant speed together. Take g = 10m / S2, 1) Find the dynamic friction between object B and desktop 2) If horizontal force F is used to pull B to the left, how much tension does it take to make objects a and B move at a uniform speed Don't let me in

As shown in the figure, the mass of object a close to the vertical side is Ma = 0.2kg, and the mass of object B on the horizontal plane is MB = 1kg, As shown in the figure, the mass of the object a on the vertical side is Ma = 0.2kg, and the mass of the object B on the horizontal plane is MB = 1kg. The weight of the rope and the friction between the rope and the pulley are not included. The OB part of the rope is horizontal, and the OA part is vertical. A and B just move at a constant speed together. Take g = 10m / S2, 1) Find the dynamic friction between object B and desktop 2) If horizontal force F is used to pull B to the left, how much tension does it take to make objects a and B move at a uniform speed Don't let me in

Analysis:
1) First select the object and analyze the force: Object B is subjected to the balance of gravity and supporting force in the vertical direction; object a is subjected to the action of sliding friction umbg and horizontal tension t in the horizontal direction; object a is subjected to the action of gravity and tension t of vertical rope. (note: regardless of the rope mass, the tension of the same rope is everywhere; the force diagram is omitted for technical reasons)
Because a and B are moving at a constant speed, the resultant force of a and B is 0. According to f = UN and Newton's law
For object B: T = μ n (1)
N=mBg （2）
For object A: T = mag (3)
Substituting the known data into the simultaneous solution, μ = 0.2
2) The research object is the same as the above question. Except for a horizontal left pulling force F added to object B, the other forces have no change
Because objects a and B move at a uniform speed, the resultant force of a and B is 0
If object B moves to the left and object a moves up, according to f = UN and Newton's law
For B, f = t + UN (1)
N=mBg （2）
For object A: T = mag (3)
Substituting known data and μ = 0.2 simultaneous solution, f = 4 (n)
If object B moves to the right and object a moves downward, according to f = UN and Newton's law
For object B, F + UN = t (1)
N=mBg （2）
For object A: T = mag (3)
Substituting the known data and μ = 0.2 simultaneous solution, f = 0.1
(Note: except for the second case, it can be directly analyzed by the first question.)