Elizabeth G.

asked • 12/18/22

PLEASE HELP ITS URGENT

A block of mass 418 g is pushed against the spring (located on the left-hand side of the track) and compresses the spring a distance 4.6 cm from its equilibrium position (as shown in the figure below). The block starts from rest, is accelerated by the compressed spring, and slides across a frictionless horizontal track (as shown in the figure below). It leaves the track horizontally, flies through the air, and subsequently strikes the ground. The acceleration of gravity is 9.81 m/s 2 .


-What is the spring constant? Answer in units of N/m.

-What is the speed v of the block when it leaves the track?

-What is the total speed of the block when it hits the ground?


1 Expert Answer

By:

Aime F. answered • 12/18/22

Tutor
4.7 (62)

PhD in Physics (Yale), have taught Methods of Engineering Analysis

Aime F.

If we solve the differential eq. m x''(t) = –k x(t), x(0) = –d, x'(0) = 0 we get x(t) = –d cos(√(k/m)t) for 0 < t < π/2√(k/m) = t₀. Therefore v = d √(k/m) sin(√(k/m)t₀) = d √(k/m) but that's the same as you got from u = e above.
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12/18/22

Aime F.

You did not include "the figure below" but if we knew the height h of the track above the ground then we can further equate kd²/2 = mv²/2 = mV²/2 – mgh for the speed V when it hits the ground. We still have 2 equations in 3 unknowns k, v and V, insufficient information.
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12/18/22

Aime F.

If we knew how far X the mass travelled horizontally from the track end then we could eliminate its falling time T between X = vT and h = gT²/2 to get h = gX²/2v², a 3rd equation whence we would have 3 equations for the 3 unknowns k, v, V. Please check that you include all information in your questions.
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12/18/22

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