A 3.0kg block is attached to a string that is wrapped around a 2.0kg , 4.0-cm-diameter hollow cylinder that is free to rotate. (Use Figure 12.34 in the textbook but treat the cylinder as hollow.) The block is released 1.0m above the ground.Use Newton's second law to find the speed of the block as it hits the ground.Use conservation of energy to find the speed of the block as it hits the ground.

Respuesta :

The speed of the block as it hits the ground is 3.4 m/s.

Calculation:

By Newton's Second Law:

The gravity of this M kg block is Mg, which causes the acceleration of itself downward and causes the rotational acceleration of the cylinder (mass m):

Mg = Ma + ((mr^2)*a/r)/r = (M+m)a

thus a = Mg/(M+m)

Since the distance of the movement is 1m, we have;

0.5*at^2 = 1, or v^2 = (at)^2 = 2a = 2Mg/(M+m)

v = sqrt(2*3.0*9.8/5.0) = 3.4 (m/s)

By conservation of energy:

The initial potential energy: Mgh = Mg

The final kinetic energy: 0.5Mv^2 + 0.5I*w^2

= 0.5Mv^2 + 0.5(m*r^2)*(v/r)^2

= 0.5*(M+m)*v^2

Before M hits the ground, all the potential energy would be converted to kinetic energy:

Mg = 0.5*(M+m)*v^2

or v = sqrt(2*M*g/(M+m)) = 3.4 (m/s)

Newton's second law states that the acceleration of an object is directly related to its net force and inversely proportional to its mass. A body's acceleration depends on its two components: force and mass.

Learn more about Newton's second law here:- https://brainly.com/question/25545050

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