Drop-load (IV) This exercise is part of a series of problems aimed at modeling a situation by progressively refining our model to take into account more and more parameters. This progressive approach is very close to what professional scientists do! Context You want to lower a suspended load in a controlled way. To do this, the suspended load (B) is connected by a rope passing through a pulley to another mass (A), which slides on a surface. It can be seen that if the suspended mass is too light, the system does not move at all. We want to determine the greatest suspended mass (B) for the system to be about to slip. Information The mass of charge A is known. The mass of the rope itself is negligible (very small compared to the loads). The pulley has negligible mass and can rotate without friction. The charge B is initially stationary and is at a known height h. The surface on which mass A sits is tilted upwards at a known angle theta from the horizontal. There is friction under mass A : the coefficients of kinetic and static friction are known. The string attached to mass A is perfectly parallel to the surface on which the mass rests. Schematization Draw a diagram of each object that interests us. Draw your x- and y-axes for each object. Draw and name each force experienced by each object that interests us. Modelization Creates a model for the maximum mass B for the system to be about to slip based on the relevant known parameters. Then test your model with the following values Mass of the load A: 80kg The initial height of suspended mass (B): 5.8m Kinetic coefficient of friction under mass A: 0.18 Coefficient of static friction under mass A: 0.39 Angle of inclination of the surface on which the mass A is placed: 13.1 degrees
Drop-load (IV)
This exercise is part of a series of problems aimed at modeling a situation by progressively refining our model to take into account more and more parameters. This progressive approach is very close to what professional scientists do!
Context
You want to lower a suspended load in a controlled way. To do this, the suspended load (B) is connected by a rope passing through a pulley to another mass (A), which slides on a surface.
It can be seen that if the suspended mass is too light, the system does not move at all. We want to determine the greatest suspended mass (B) for the system to be about to slip.
Information
The mass of charge A is known.
The mass of the rope itself is negligible (very small compared to the loads).
The pulley has negligible mass and can rotate without friction.
The charge B is initially stationary and is at a known height h.
The surface on which mass A sits is tilted upwards at a known angle theta from the horizontal.
There is friction under mass A : the coefficients of kinetic and static friction are known.
The string attached to mass A is perfectly parallel to the surface on which the mass rests.
Schematization
Draw a diagram of each object that interests us. Draw your x- and y-axes for each object. Draw and name each force experienced by each object that interests us.
Modelization
Creates a model for the maximum mass B for the system to be about to slip based on the relevant known parameters.
Then test your model with the following values
Mass of the load A: 80kg
The initial height of suspended mass (B): 5.8m
Kinetic coefficient of friction under mass A: 0.18
Coefficient of static friction under mass A: 0.39
Angle of inclination of the surface on which the mass A is placed: 13.1 degrees
Step by step
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