contestada

A spring of constant 20 N/m has compressed a distance 8 m by a(n) 0.3 kg mass, then released. It skids over a frictional surface of length 2 m with a coefficient of friction 0.16, then compresses the second spring of constant 2 N/m. The acceleration of gravity is 9.8 m/s2.
How far will the second spring compress in order to bring the mass to a stop?

Respuesta :

Answer:

[tex]X_2=25.27m[/tex]

Explanation:

Here we will call:

1. [tex]E_1[/tex]: The energy when the first spring is compress

2. [tex]E_2[/tex]: The energy after the mass is liberated by the spring

3. [tex]E_3[/tex]: The energy before the second string catch the mass

4. [tex]E_4[/tex]: The energy when the second sping compressed

so, the law of the conservations of energy says that:

1. [tex]E_1 = E_2[/tex]

2. [tex]E_2 -E_3= W_f[/tex]

3.[tex]E_3 = E_4[/tex]

where [tex]W_f[/tex] is the work of the friction.

1. equation 1 is equal to:

[tex]\frac{1}{2}Kx^2 = \frac{1}{2}MV_2^2[/tex]

where K is the constant of the spring, x is the distance compressed, M is the mass and [tex]V_2[/tex] the velocity, so:

[tex]\frac{1}{2}(20)(8)^2 = \frac{1}{2}(0.3)V_2^2[/tex]

Solving for velocity, we get:

[tex]V_2[/tex] = 65.319 m/s

2. Now, equation 2 is equal to:

[tex]\frac{1}{2}MV_2^2-\frac{1}{2}MV_3^2 = U_kNd [/tex]

where M is the mass, [tex]V_2[/tex] the velocity in the situation 2, [tex]V_3[/tex] is the velocity in the situation 3, [tex]U_k[/tex] is the coefficient of the friction, N the normal force and d the distance, so:

[tex]\frac{1}{2}(0.3)(65.319)^2-\frac{1}{2}(0.3)V_3^2 = (0.16)(0.3*9.8)(2) [/tex]

Volving for [tex]V_3[/tex], we get:

[tex]V_3 = 65.27 m/s[/tex]

3. Finally, equation 3 is equal to:

[tex]\frac{1}{2}MV_3^2 = \frac{1}{2}K_2X_2^2[/tex]

where [tex]K_2[/tex] is the constant of the second spring and [tex]X_2[/tex] is the compress of the second spring, so:

[tex]\frac{1}{2}(0.3)(65.27)^2 = \frac{1}{2}(2)X_2^2[/tex]

solving for [tex]X_2[/tex], we get:

[tex]X_2=25.27m[/tex]