What Are the Mass and Friction Coefficient for the Blocks?

  • Thread starter Thread starter EPFLstudent
  • Start date Start date
AI Thread Summary
The discussion revolves around analyzing the motion of two blocks with different masses and determining the dynamic friction coefficient between the larger block and the surface. When the smaller block's mass is 3kg, the larger block accelerates at 0.6 m/s², and at 4kg, it accelerates at 1.6 m/s². The relationship between the movements of the two blocks is established, with the smaller block moving twice as much as the larger block. Participants emphasize the importance of free body diagrams to understand the forces acting on the smaller block. The goal is to derive expressions for their motions and calculate the mass of the larger block and the friction coefficient.
EPFLstudent
Messages
2
Reaction score
0
Figure attached below. You have a big block of mass M and a small block of mass m. When m=3kg, the acceleration of the large block is 0.6ms-2. When m=4kg, the acceleration of the large block is 1.6ms-2. The dynamic friction coefficient between the large block and the surface it slides on is μ. There is no friction between any other surface. Questions:

a) Express the relationship between the movement of block m and block M
b) Derive expressions for the motion of block m and block M.
c) Determine the mass of block M and the dynamic friction coefficient, μ, between it and the surface it slides on.

FDmZ7.jpg
 
Last edited:
Physics news on Phys.org
Nice problem. So what have you got so far? How does the motion of mass m relate to the motion of mass M?
 
I know that x_m = 2 x_M, so that the small block moves two times as much as the big block. My problem is decomposing the forces.
 
Draw free body diagrams. Start with the mass m. What forces are acting on m?
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Thread 'Electric field due to charges between 2 parallel infinite planes'

TL;DR Summary: Find Electric field due to charges between 2 parallel infinite planes using Gauss law at any point Here's the diagram. We have a uniform p (rho) density of charges between 2 infinite planes in the cartesian coordinates system. I used a cube of thickness a that spans from z=-a/2 to z=a/2 as a Gaussian surface, each side of the cube has area A. I know that the field depends only on z since there is translational invariance in x and y directions because the planes are...
View full post »

Similar threads

Finding the work done by a block
Replies
4
Views
3K
Newton's law problem: Pushing 2 stacked blocks on a horizontal table
Replies
13
Views
3K
Friction problem of a block sandwiched between 2 surfaces
Replies
6
Views
1K
Calculating Force and Acceleration in a Two Block System with Varying Friction
Replies
6
Views
1K
Two blocks kept side by side and friction between them
Replies
9
Views
2K
Variable friction on an inclined plane and maximum velocity
Replies
33
Views
3K
Why Does the Friction Force Not Match in the Two Block Problem?
Replies
15
Views
3K
What is the relationship between tension and mass in a system with friction?
Replies
6
Views
2K
Plotting the graph of Friction Force vs. time (Laws of motion)
Replies
1
Views
2K
Can a 10N Force Overcome Friction to Move a 10kg Block?
Replies
2
Views
1K

Hot Threads

Recent Insights

Back
Top