Halfway done Force/Friction Problem

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Homework Help Overview

The problem involves a block on an inclined plane connected to a hanging block, focusing on forces, friction, and acceleration to determine the speed of the falling block after a certain distance. The subject area includes dynamics and friction in physics.

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  • Mixed

Approaches and Questions Raised

  • Participants discuss the calculation of forces acting on both blocks, including gravitational, normal, and frictional forces. There are attempts to derive acceleration and speed based on these forces. Some participants question the correctness of their calculations and seek verification of their results.

Discussion Status

The discussion includes various calculations and attempts to verify the results. Some participants have provided guidance on using kinematic equations to find speed after determining acceleration. There is an ongoing request for confirmation of the solutions presented.

Contextual Notes

Participants express uncertainty about their calculations and seek validation before submission. There is a focus on ensuring that all forces and their directions are correctly accounted for in the problem setup.

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A block of mass m1 = 290 g is at rest on a plane that makes an angle θ = 30° above the horizontal. The coefficient of kinetic friction between the block and the plane is µk = 0.10. The block is attached to a second block of mass m2 = 220 g that hangs freely by a string that passes over a frictionless and massless pulley.
Find its speed when the second block has fallen 30.0 cm.
cm/s

What I have done:
I turned the 2 masses into kg.

M1 = .29kg and M2 = .22kg
M1 Force of Gravity = .29kg * 9.81 m/s^2 = 2.8N
M1 Normal Force = 28 * cos30 = 2.4N
M1 Parallel Force = 28 * sin30 = 1.4N
M1 Friction Force = .10 * 2.4 = .24N

M2 Force of Gravity = 2.1N

This where I am stuck, I don't know what I should do next to determine the speed of M2 when it is falling.Edit:

The Net Force would be
1.4N - .24N = 1.16N
= 2.1N - 1.16N = .94N

F = M * A
.94N = .51kg * A
A = 1.8 m/s^2

Since there is 100 centimeters in a meter
so A = 180 cm/S^2

Speed = Distance * Time
X = 30cm * T
Where T = 30/180 = .17s
30 * .17s
Speed = 5.1cm/s

Is this correct?
 
Last edited:
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The Net Force would be
1.4N - .24N = 1.16N
= 2.1N - 1.16N = .94N

The friction force on m1 acts opposite the direction of motion of m1 with respect to the inclined plane and so it acts down the plane.

Once a is found, you can use v = a t and d = (1/2) a t^2 to find v.
 
I found
F = M * A
.94N = .51kg * A
A = 1.8 m/s^2

Since there is 100 centimeters in a meter
so A = 180 cm/S^2

I found Time to be .58s
V = to be 104cm/s

Is this correct?
 
Can someone verify if this is the correct solution? Thanks!
 
Anyone? I just need to verify this solution before I submit it online, please.
 

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