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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?

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# Homework Help: Halfway done Force/Friction Problem

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