Fysikk hjelp (fys-mek oblig)

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madde-2

Kan noen hjelpe meg med disse oppgavene?

Here, we will introduce and study a model for stick-slip friction for a block pulled by a spring sliding over a flat, horizontal surface, as illustrated in figure 0.1.
The block has mass m. A massless spring (with spring constant k and equilibrium length b) is attached to the block at the point x. The free end (the right-hand end in figure 0.1) of the spring is at the point xb. We move xb, the free end of the spring, with a constant velocity u. The static and dynamic coefficients of friction for the contact between the block and the bottom surface are μs and μd respectively. The acceleration of gravity is g = 9.8m/s2.
The block starts at the position x(t0) = 0 at the time t0 = 0. The position xb of the free end of the spring is xb(t0) = x(t0) + b at t0.

(b) Find the position of the spring attachment point xb(t) as a function of time.
(c) Show that the force, F⃗ on the block from the spring is:
F⃗ = k(xb − x − b)ˆi .
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