13. Rotational Inertia & Energy

Intro to Moment of Inertia

13. Rotational Inertia & Energy

Intro to Moment of Inertia

Guided videos.

A system is made of two small masses (M_LEFT = 3 kg, M_RIGHT = 4 kg) attached to the ends of a 5 kg, 2-m long thin rod, as shown. Calculate the moment of inertia of the system if it spins about a perpendicular axis through the mass on the left.

A solid disc 4 m in diameter has a moment of inertia equal to 30 kg m² about an axis through the disc, perpendicular to its face. The disc spins at a constant 120 RPM. Calculate the mass of the disc.

A mechanic gives a bicycle tire a spin causing it to rotate at 2.3 rpm. If the mechanic was pushing for

0.5 s

, what was the average angular acceleration of the wheel while it was speeding up.

371

views

Multiple Choice

The figure shows all the forces acting on a

2.0 kg

solid disk of diameter

4.0 cm

. What is the magnitude of the disk's angular acceleration?

322

views

Textbook Question

CALC A slender rod with length L has a mass per unit length that varies with distance from the left end, where x = 0, according to dm/dx = gx, where g has units of kg/m^2. (b) Use Eq. (9.20) to calculate the moment of inertia of the rod for an axis at the left end, perpendicular to the rod. Use the expression you derived in part (a) to express I in terms of M and L. How does your result compare to that for a uniform rod? Explain.

1241

views

Textbook Question

You are a project manager for a manufacturing company. One of the machine parts on the assembly line is a thin, uniform rod that is 60.0 cm long and has mass 0.400 kg. (a) What is the moment of inertia of this rod for an axis at its center, perpendicular to the rod?

Calculate the moment of inertia of each of the following uniform objects about the axes indicated. Consult Table 9.2 as needed. (a) A thin 2.50-kg rod of length 75.0 cm, about an axis perpendicular to it and passing through (i) one end and (ii) its center, and (iii) about an axis parallel to the rod and passing through it.

657

views

Textbook Question

If we multiply all the design dimensions of an object by a scaling factor f, its volume and mass will be multiplied by f^3. (a) By what factor will its moment of inertia be multiplied?

240

views

Textbook Question

An object whose moment of inertia is 4.0 kg m^2 is rotating with angular velocity 0.25 rad/s. It then experiences the torque shown in FIGURE EX12.25. What is the object's angular velocity at t = 3.0s?

The three masses shown in FIGURE EX12.15 are connected by massless, rigid rods. (b) Find the moment of inertia about an axis that passes through mass A and is perpendicular to the page.

881

views

Textbook Question

The three 200 g masses in FIGURE EX12.11 are connected by massless, rigid rods. (b) What is the triangle's kinetic energy if it rotates about the axis at 5.0 rev/s?

482

views

Textbook Question

The four masses shown in FIGURE EX12.13 are connected by massless, rigid rods. (b) Find the moment of inertia about a diagonal axis that passes through masses B and D.

1093

views

Textbook Question

A rod of length L and mass M has a nonuniform mass distribution. The linear mass density (mass per length) is λ = cx^2 , where x is measured from the center of the rod and c is a constant. c. Find an expression in terms of L and M for the moment of inertia of the rod for rotation about an axis through the center.

views

Textbook Question

A 70.0-kg person stands on a tiny rotating platform with arms outstretched.

(a) Estimate the moment of inertia of the person using the following approximations: the body (including head and legs) is a 62.0-kg cylinder, 16 cm in radius and 1.70 m high; and each arm is a 4.0-kg thin rod, 60.0 cm long, attached to the cylinder.

135

views

Textbook Question

A 12-cm-diameter DVD has a mass of 21 g. What is the DVD’s moment of inertia for rotation about a perpendicular axis (a) through its center?

views

Showing 15 of 15 practice