Honors Physics 2023-24 Test 6 Notes

Honors Physics 2023-24 Test 6 Notes

Part I: Multiple Choice

  • Each question is worth 3 points.

  • No partial credit is awarded.

Question 1

  • A 43 gram newt is on a ceiling fan blade at a radius of 85 cm.

  • The fan takes 4.0 s to make ten complete revolutions.

  • What is the period of the newt's motion?

  • Period T is the time for one complete revolution.

  • T = \frac{4.0 \text{ s}}{10} = 0.40 \text{ s}

Question 2

  • What is the constant speed of the newt in its circular motion?

  • Radius r = 85 \text{ cm} = 0.85 \text{ m}

  • Period T = 0.40 \text{ s}

  • Circumference C = 2\pi r = 2 \pi (0.85 \text{ m}) = 5.34 \text{ m}

  • Speed v = \frac{C}{T} = \frac{5.34 \text{ m}}{0.40 \text{ s}} = 13.35 \text{ m/s} \approx 13 \text{ m/s}

Question 3

  • An object is in circular motion with constant speed.

  • Which statement is true?

  • The speed is constant, but the velocity is constantly changing because direction changes.

  • Acceleration is not zero because the velocity changes direction.

Question 4

  • SuYi weighs 750 N. She jumps straight up.

  • What is the force magnitude exerted by SuYi on the Earth at her highest point?

  • Weight is the force of gravity. At the highest point, SuYi still has weight (force due to gravity).

  • According to Newton's Third Law, forces are equal and opposite. Therefore, the magnitude of the force exerted by SuYi on the Earth is 750 N.

Question 5

  • The period of rotation of an object with angular speed 52 \text{ rad/s} is equal to what?

  • Angular speed \omega = 52 \text{ rad/s}

  • \omega = \frac{2\pi}{T}

  • T = \frac{2\pi}{\omega} = \frac{2\pi}{52 \text{ rad/s}} = 0.12 \text{ s}

Question 6

  • A rotating amusement park ride completes 6 rotations in one minute.

  • What is its frequency of rotation?

  • 6 rotations per minute = 6/60 rotations per second = 0.1 Hz.

Question 7

  • A block of mass m is pushed against a rough wall by a force P.

  • Frictional force is f, and normal force is F_N.

  • Which FBD correctly shows all forces on the block?

Question 8

  • If the block is not moving in the previous question, the magnitude of f is equal to what?

  • If the block is not moving, the forces balance.

  • Vertical forces: friction (up) and weight (down).

  • f = mg. The magnitude of the force f equals the magnitude of the weight (mg).

Question 9

  • In lab, water drips from a hole in a beaker at rate R (in cm\text{cm}^3/min) as a function of depth d (in cm).

  • R = \alpha d^3, where \alpha is a constant.

  • Data is plotted as R vs. d^3, with EXCEL giving y = 7.63x + 0.0021.

  • What are the units of 7.63?

  • R is in cm\text{cm}^3/min, d^3 is in cm\text{cm}^3 . The slope is \frac{R}{d^3}, so the units are \frac{\text{cm}^3/\text{min}}{\text{cm}^3} = 1/\text{min}.

Question 10

  • What are the units of 0.0021 in the EXCEL equation?

  • The y-intercept has the same units as y (which is R).

  • Units are cm\text{cm}^3/min.

Question 11

  • The experimental value of the constant \alpha is what?

  • From the equation y = 7.63x + 0.0021, the slope is 7.63. Therefore, \alpha = 7.63 /\text{min}.

  • The question asks for \frac{1}{\alpha}, so \frac{1}{7.63} = 0.13 \text{ min}.

Question 12

  • 21.7 \text{ m} = __

Question 13

  • A wave on a rope has \lambda = 25.7 \text{ cm}.

  • In 1.32 \text{ s}, 3 crests pass you.

  • What is the speed of the wave?

  • f = \frac{3}{1.32 \text{ s}} = 2.27 \text{ Hz}

  • v = \lambda f = 25.7 \text{ cm} \times 2.27 \text{ Hz} = 58.3 \text{ cm/s}

Question 14

  • A wave has a period of 583 \text{ ns}.

  • What is its frequency?

  • T = 583 \text{ ns} = 583 \times 10^{-9} \text{ s}

  • f = \frac{1}{T} = \frac{1}{583 \times 10^{-9} \text{ s}} = 1.7 \times 10^6 \text{ Hz} = 1.7 \text{ MHz}

Question 15

  • The wavelength of indigo light is closest to _ .

Question 16

  • A light wave travels from one medium into another with a higher index of refraction.

  • Which statements are true?

    • I. The transmitted wave is closer to the normal than the incident wave.

    • II. The transmitted wave has a smaller frequency than the incident wave.

    • III. The transmitted wave has a higher speed than the incident wave.

Question 17

  • Which of the following is an example of a transverse wave?

    • I. sound

    • II. light

    • III. seismic

Question 18

  • It takes a mass 3.5 minutes to travel around a circle 25 times.

  • The angular speed of the mass is _ rad/s.

  • Time = 3.5 min = 210 seconds.

  • \omega = \frac{\Delta \theta}{\Delta t} = \frac{25 \cdot 2\pi \text{ rad}}{210 \text{ s}} = \frac{157 \text{ rad}}{210 \text{ s}} = 0.75 \text{ rad/s}

Question 19

  • Which of the following lists wavelengths from shortest to longest?

Question 20

  • A book sits at rest on a table top. The normal force and the weight of the cup form an action-reaction pair since .

Part II: Problems

Problem 1

  • A 3.2-kg block is kicked up an incline (width 32 cm, height 8.3 cm) with an initial speed of 2.7 m/s.

  • It slides 42 cm along the incline before stopping.

    • (a) What is the acceleration of the block as it slides up the incline?

    • (b) Draw a good FBD for the block as it slides up the incline.

    • (c) What is the value of the apparent weight of the block as it slides up the incline?

    • (d) What is the value of the coefficient of friction between the block and the incline?

Problem 2

  • A car starts at rest at point P. It accelerates to point Q (370 m away), then drives around a circular track of radius 200 m.

  • Speed at point Q is 45 m/s. It continues around the track at a constant speed of 45 m/s.

    • (a) What was the acceleration of the car as it moved from point P to point Q?

    • (b) How long did it take the car to drive around the track 15 times?

    • (c) What was the frequency, f, of the car’s motion around the circular track?

    • (d) What was the angular speed of the car in its motion around the circular track as seen from the center of the circle?

    • (e) Through what angle \Delta \theta (in radians) did the car move as seen by someone at the center of the track during a time interval of 2.3 s?