6.4.4 Work and Power in Rotational Motion

Question 1

Work and Power in Rotational Motion

Answer 1

• The quantities and formulas used to describe and explain rotational motion are analogous to those used to describe and explain linear motion.
• The equation is the rotational analogue of

Question 2

A whell of mass M and radius R is rotating with angular velocity w on a horizontal axle. Consider the wheel as a solid disk. The kinetic energy of the wheel is ________

Answer 2

greatest if the mass is concentrated near the rim

Question 3

The following list is an analog between linear (translational) and angular (rotational) motion. Which of the following is not correct?

Answer 3

K = 1/2mv; K=1/2Iw

Question 4

Which of the following statements about kinetic energy is not correct?

Answer 4

The kinetic energy of a rigid body rotating at 8 rad / s has twice the kinetic energy as a rigid body rotating rigid body at 4 rad / s.

Question 5

Suppose that an engine is rated at 185.00 hp at 4,500 rev / min. How much torque does the engine produce at that rpm?

Answer 5

292.75 Nm

Question 6

A spool of string mounted on a wall has a radius of 0.12 m and a mass of 6.2 kg. Suppose that we pull on the string’s free end with a force of 5.2 N for a time period of 2 s. What is the work done by the force during the two-second time period?

Answer 6

17.5 Nm

Question 7

A car engine delivers 380 Nm of torque at 3,200 rev/min. What is the power output of the engine?

Answer 7

127 kW

Question 8

The rotational analog of power in translational motion is rotational power. Which of the following is not correct.

Answer 8

P = W/t; t theta/t; tw; Its unit is horsepower

Question 9

Which of the following is not correct?

Answer 9

Because delta K = 1/2lw^2 - 1/2lw0^2, a torque is not needed to change the rotational kinetic energy of an object