Drop-load (II) 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 step-by-step approach is very close to what professional scientists do! Context We want to lower a suspended load in a controlled way, so that it hits the ground with a speed whose modulus is not too large. To do this, the suspended load (B) is connected by a rope passing through a pulley to another mass (A), which slides on a horizontal surface. Information The masses of the charges A and B are known. The mass of the rope itself is negligible (very small compared to the loads). The pulley has a negligible mass and can turn without rubbing. The charge B is initially stationary and is at a known height h. The surface on which the mass A is placed is horizontal. There is friction under the mass A: the kinetic friction coefficient is known. The string attached to mass A is perfectly parallel to the surface on which the mass is resting. 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. Caution: Do not give the same name to two different forces, unless their module is the same! Modelization Create a model for the modulus of the speed at which the load B will hit the ground as a function of the value of the masses A and B, as well as the initial height of the block B and the kinetic friction coefficient only. Then test your model with the following values Mass of the load ?: 85kg; Mass of suspended load (?): 66kg; Initial height of suspended mass (h): 3.1m Friction coefficient under mass A : 0.42
Drop-load (II)
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 step-by-step approach is very close to what professional scientists do!
Context
We want to lower a suspended load in a controlled way, so that it hits the ground with a speed whose modulus is not too large. To do this, the suspended load (B) is connected by a rope passing through a pulley to another mass (A), which slides on a horizontal surface.
Information
The masses of the charges A and B are known.
The mass of the rope itself is negligible (very small compared to the loads).
The pulley has a negligible mass and can turn without rubbing.
The charge B is initially stationary and is at a known height h.
The surface on which the mass A is placed is horizontal.
There is friction under the mass A: the kinetic friction coefficient is known.
The string attached to mass A is perfectly parallel to the surface on which the mass is resting.
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.
Caution: Do not give the same name to two different forces, unless their module is the same!
Modelization
Create a model for the modulus of the speed at which the load B will hit the ground as a function of the value of the masses A and B, as well as the initial height of the block B and the kinetic friction coefficient only.
Then test your model with the following values
Mass of the load ?: 85kg;
Mass of suspended load (?): 66kg;
Initial height of suspended mass (h): 3.1m
Friction coefficient under mass A : 0.42
Step by step
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