Cutnell/Johnson Physics 8 th edition

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# Cutnell/Johnson Physics 8 th edition - PowerPoint PPT Presentation

Cutnell/Johnson Physics 8 th edition. Classroom Response System Questions. Chapter 8 Rotational Kinematics. Reading Quiz Questions. 8.1.1. Angles are often measured in radians. How many degrees are there in one radian? a) 0.0175  b) 1.57  c) 3.14  d) 16.3  e) 57.3 .

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Cutnell/JohnsonPhysics 8th edition

• Classroom Response System Questions

Chapter 8 Rotational Kinematics

8.1.1. Angles are often measured in radians. How many degrees are there in one radian?

a) 0.0175

b) 1.57

c) 3.14

d) 16.3

e) 57.3

8.1.2. The SI unit for angular displacement is the radian. In calculations, what is the effect of using the radian?

a) Any angular quantities involving the radian must first be converted to degrees.

b) Since the radian is a unitless quantity, there is no effect on other units when multiplying of dividing by the radian.

c) Since the radian is a unitless quantity, any units multiplied or divided by the radian will be equal to one.

d) Since the radian is a unitless quantity, the number of radians of angular displacement plays no role in the calculation.

e) The result of the calculation will always have the radian among the units.

8.1.3. For a given circle, the radian is defined as which one of the following expressions?

a) the arc length divided by the radius of the circle

b)  (3.141592...) times twice the radius of the circle

c) two times ninety degrees divided by  (3.141592...)

d) the arc length divided by the circumference of the circle

e) the arc length divided by the diameter of the circle

8.2.1. The hand on a stopwatch makes one complete revolution every three seconds. Express the angular speed of this hand in radians per second.

8.2.2. A drill bit in a hand drill is turning at 1200 revolutions per minute (1200 rpm). Express this angular speed in radians per second (rad/s).

a) revolutions per minute (rpm)

b) meters per second (m/s)

c) degrees per minute (/min)

e) tychos per second (ty/s)

8.2.4. The jet engine has angular acceleration of 2.5 rad/s2. Which one of the following statements is correct concerning this situation?

a) The direction of the angular acceleration is counterclockwise.

b) The direction of the angular velocity must be clockwise.

c) The angular velocity must be decreasing as time passes.

d) If the angular velocity is clockwise, then its magnitude must increase as time passes.

e) If the angular velocity is counterclockwise, then its magnitude must increase as time passes.

8.3.1. Which one of the following equations is only valid when the angular measure is expressed in radians?

a)

b)

c)

d)

e)

8.3.2. Consider the following situation: one of the wheels of a motor cycle is initially rotating at 39 rad/s. The driver then accelerates uniformly at 7.0 rad/s2 until the wheels are rotating at 78 rad/s. Which one of the following expressions can be used to find the angular displacement of a wheel during the time its angular speed is increasing?

a)

b)

c)

d)

e)

8.4.1. A deep space probe is rotating about a fixed axis with a constant angular acceleration. Which one of the following statements concerning the tangential acceleration of any point on the probe is true?

a) The probe’s tangential acceleration is constant in both magnitude and direction.

b) The magnitude of the probe’s tangential acceleration is zero m/s2.

c) The tangential acceleration depends on the angular velocity of the probe.

d) The tangential acceleration is to equal the centripetal acceleration of the probe.

e) The tangential acceleration depends on the change in the probe’s angular velocity.

8.4.2. Two points are located on a rigid wheel that is rotating with a decreasing angular velocity about a fixed axis. Point A is located on the rim of the wheel and point B is halfway between the rim and the axis. Which one of the following statements is true concerning this situation?

a) Both points have the same centripetal acceleration.

b) Both points have the same instantaneous angular velocity.

c) Both points have the same tangential acceleration.

d) Each second, point A turns through a greater angle than point B.

e) The angular velocity at point A is greater than that of point B.

8.5.1. As an object rotates, its angular speed increases with time. Complete the following statement: The total acceleration of the object is given by

• the vector sum of the centripetal acceleration and the tangential acceleration.
• b) the vector sum of the angular velocity and the tangential acceleration divided by the elapsed time.
• c) the angular acceleration.
• d) the centripetal acceleration.
• e) the tangential acceleration.

8.5.2. Which one of the following statements correctly relates the centripetal acceleration and the angular velocity?

a) The centripetal acceleration is the product of the radius and the square of the angular velocity.

b) The centripetal acceleration is the square of the angular velocity divided by the radius.

c) The centripetal acceleration is the product of the radius and the angular velocity.

d) The centripetal acceleration is the angular velocity divided by the radius.

e) The centripetal acceleration is independent of the angular velocity.

8.6.1. A wheel is rolling without slipping along a straight, level road. Which one of the following statements concerning the speed of the center of the wheel is true?

a) A point on the rim is moving at a tangential speed that is equal to the speed at the center of the wheel.

b) A point on the rim is moving at a tangential speed that is one-half the speed at the center of the wheel.

c) A point on the rim is moving at a tangential speed that is two times the speed at the center of the wheel.

d) A point on the rim moves at a speed that is not related to the speed at the center of the wheel.

e) A point on the rim is moving at a tangential speed that varies as the wheel rotates, but the speed at the center of the wheel is constant.

8.6.2. The wheels of a NASCAR racer roll without slipping as the car moves in a circular path at constant speed. Which one of the following quantities has a non-zero value and has a constant value in this situation?

a) linear velocity

b) centripetal acceleration

c) angular velocity

d) angular acceleration

e) total acceleration

8.6.3. At the post office, a customer has dropped a coin. The coin is rolling on its side across the floor. Which one of the following statements concerning this situation is true?

a) The tangential velocity is the same for all points on the side of the coin.

b) There is no slipping at the point where the coin touches the floor.

c) The angular acceleration of the coin must be zero m/s2.

d) The tangential velocity is the same for all points on the coin.

e) The linear velocity for all points on the coin is non-zero.

8.7.1. The wheels of a bicycle roll without slipping on a horizontal road. The bicycle is moving due east at a constant velocity. What is the direction of the angular velocity of the wheels?

a) down

b) west

c) east

d) north

e) south

8.7.2. While putting in a new ceiling, Jake uses a drill to put screws into the drywall. The screws rotate clockwise as they go into the ceiling. What is the direction of the angular velocity of the screw as the drill drives it into the ceiling? Express the direction relative to Jake, who is looking upward at the screw.

a) down

b) up

c) left

d) right

e) forward