Minimum force required to keep two blocks from not falling

In summary, the minimum force required to keep two blocks from falling depends on factors such as their weights, the angle of inclination, and the friction between the blocks and the surface. The force must counteract the gravitational pull on the blocks and any additional forces acting on them, ensuring they remain stationary. Calculating this force involves applying principles of static equilibrium and frictional forces.
  • #1
nafisanazlee
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2
Homework Statement
Two blocks P and Q are of weight 20N and 100N, respectively. These are being pressed against a wall by a force F as shown. If the coefficient of static friction between the blocks is 0.1 and between block Q and the wall is 0.15, what will be the minimum force to keep the blocks in equilibrium?
I've tried to solve it in this way, but I'm not sure if my approach is correct or not. Can you please check?
Relevant Equations
Fsmax = μsN
CamScanner 11-26-2023 02.56.jpg
 
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  • #2
:welcome:

Looks right. You might want to add why block P does not slide.
 
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  • #3
PeroK said:
:welcome:

Looks right. You might want to add why block P does not slide.
because the maximum friction force that can be provided between the two blocks becomes 0.1*800= 80N, and we only need 20N for support, so it's fine..?
 
  • #4
nafisanazlee said:
because the maximum friction force that can be provided between the two blocks becomes 0.1*800= 80N, and we only need 20N for support, so it's fine..?
Yes, it was fairly obvious from the numbers that the maximum force was needed for Q (as it is much heavier). But, it does no harm to show the calculation for P as well.
 
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  • #5
PeroK said:
Yes, it was fairly obvious from the numbers that the maximum force was needed for Q (as it is much heavier). But, it does no harm to show the calculation for P as well.
Thank you so much for your time. Much appreciated.
 
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FAQ: Minimum force required to keep two blocks from not falling

What is the minimum force required to keep two blocks from falling?

The minimum force required to keep two blocks from falling depends on the frictional forces between the blocks and the surfaces they are in contact with. If we assume the blocks are stacked and there is friction between them, the minimum force is calculated using the coefficient of friction and the normal force exerted by the blocks' weights.

How do you calculate the frictional force between two blocks?

The frictional force (F_friction) can be calculated using the equation F_friction = μ * N, where μ is the coefficient of friction between the surfaces and N is the normal force. The normal force is typically the weight of the block, which can be calculated as N = m * g, where m is the mass of the block and g is the acceleration due to gravity.

What role does the coefficient of friction play in determining the minimum force?

The coefficient of friction (μ) is a measure of how much frictional force exists between two surfaces. A higher coefficient of friction means more force is needed to overcome the friction and keep the blocks from falling. It directly affects the calculation of the frictional force, which in turn determines the minimum force required.

Does the mass of the blocks affect the minimum force required to keep them from falling?

Yes, the mass of the blocks directly affects the normal force, which is a component in calculating the frictional force. A heavier block will exert a greater normal force, resulting in a higher frictional force, and thus a greater minimum force required to keep the blocks from falling.

Can the minimum force be zero if the coefficient of friction is very high?

In theory, if the coefficient of friction is extremely high, the frictional force could be sufficient to keep the blocks from falling without any additional applied force. However, in practical scenarios, there is always some force needed to ensure stability, especially if there are external disturbances or if the surfaces are not perfectly static.

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