Beginning from rest, an object of mass 200 kg slides down a 8-m-long ramp. The ramp is inclined at an angle of 20⁰ from the horizontal. If air resistance and friction between the object and the ramp are negligible, determine the velocity ofthe object, in m/s, at the bottom of the ramp. Let g = 9.81m/s².

Respuesta :

Answer:

The velocity at the bottom of the ramp is 7.32 m/s

Solution:

As per the question:

Mass of the object, m = 200 kg

Length of the rope, l = 8 m

Angle of inclination of the ramp, [tex]\theta = 20^{\circ}[/tex]

g = 9.81 [tex]m/s^{2}[/tex]

Now,

The overall mechanical energy of the system will remain conserved:

Mechanical energy at the top = Mechanical energy at the bottom

[tex]KE_{top} + PE_{top} = KE_{bot} + PE_{bot}[/tex]         (1)

where

[tex]KE_{top}[/tex] = Kinetic Energy at the top

[tex]PE_{top}[/tex] = Potential Energy at the top

[tex]KE_{bot}[/tex] = Kinetic Energy at the bottom

[tex]KE_{bot}[/tex] = Kinetic Energy at the bottom

Potential energy at the top is min and potential energy at the top is maximum whereas potential energy at the bottom is minimum and kinetic energy is maximum

Thus, using eqn (1):

[tex]\frac{1}{2}mv^{2}_{top} + mgh_{top} = \frac{1}{2}mv^{2}{bot} + mgh_{bot}[/tex]  

where velocity at the top is minimum and zero and height at the bottom is zero.

Also, the object slides along the inclined plane and hence the height, h = [tex]l\sin\theta[/tex]

Thus

[tex]\frac{1}{2}m.0^{2}_{top} + 200\times 9.8\times lsin\theta = \frac{1}{2}mv^{2}{bot} + mg.0[/tex]  

[tex]200\times 9.8\times 8sin20 = \frac{1}{2}\times 200v^{2}{bot}[/tex]  

[tex]v_{bot} = \sqrt{2\times 26.81} = 7.32\ m/s[/tex]

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