An exhausted bicyclist pedals somewhat erratically when exercising on a static bicycle. The angular velocity of the wheels follows the equation ω(t)=at−bsin(ct)fort≥0, where t represents time (measured in seconds), a = 0.500 rad/s2 , b = 0.250 rad/s and c = 2.00 rad/s .
Part A
There is a spot of paint on the front wheel of the bicycle. Take the position of the spot at time t=0 to be at angle θ=0 radians with respect to an axis parallel to the ground (and perpendicular to the axis of rotation of the tire) and measure positive angles in the direction of the wheel's rotation. What angular displacement θ has the spot of paint undergone between time 0 and 2 seconds?
Part B
Express the angular displacement undergone by the spot of paint at t=2 seconds in degrees. Remember to use the unrounded value from Part A, should you need it.
Express your answer in degrees using three significant figures.
Part C
What distance d has the spot of paint moved in 2 seconds if the radius of the wheel is 50 centimeters?
Part D
Which one of the following statements describes the motion of the spot of paint at t=2.0 seconds?
Which one of the following statements describes the motion of the spot of paint at seconds?
| A)The angular acceleration of the spot of paint is constant and the magnitude of the angular speed is decreasing. | |
| B) | The angular acceleration of the spot of paint is constant and the magnitude of the angular speed is increasing. |
| C) | The angular acceleration of the spot of paint is positive and the magnitude of the angular speed is decreasing. |
| D) | The angular acceleration of the spot of paint is positive and the magnitude of the angular speed is increasing. |
| E) | The angular acceleration of the spot of paint is negative and the magnitude of the angular speed is decreasing. |
| F) | The angular acceleration of the spot of paint is negative and the magnitude of the angular speed is increasing. |
In: Physics
In a drag race, the position of a car as a function of time is given by x=bt2, with b = 2.045m/s2 . In an attempt to determine the car's velocity midway down a 400-m track, two observers stand at the 165-m and 235-m marks and note the time when the car passes.What value do the two observers compute for the car's velocity over this 70m stretch?
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The reflecting surfaces of two intersecting flat mirrors are at an angle of 57?, as shown in the figure. A light ray strikes the horizontal mirror at an angle of 57? with respect to the mirror
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You are given displacement equation for object in SHM as: x(t)=1.5cos(3.0t) cm.
a) The period of this oscillation is: [ Select ] ["2.1 sec", "3 sec", "1.5 sec", "0.48 sec"]
b) The amplitude of the motion is: [ Select] ["0.75 m", "1.5 m", "3.0 m"]
c) The maximum velocity is: [ Select ] ["28 m/s", "4.5 m/s", "0.72 m/s"]
d) The displacement at t = 0.5 s is [ Select ] ["0.12 m", "-0.78 m", "1.5 m"]
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A 4.2 kg lead ball is dropped into a 2.4 L insulated pail of water initially at 20.0∘C.
If the final temperature of the water-lead combination is 26.0 ∘C, what was the initial temperature of the lead ball?
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What are the three most common types of radioactive decays? How do they differ? Also how many types of decays are there? Please describe them.
In: Physics
Chapter 2, #31
You are driving through town at 12 m/s when suddenly a car backs out of a driveway in front of you. You apply the brakes and begin decelerating at 3.3 m/s2. How much time does it take to stop? After braking half the time found in part A, is your speed 6.0 m/s, greater than 6.0 m/s, or less than 6.0 m/s?
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1. 1. In polarizing microscopy, what is and what happens when a sample is anisotropic?
2. 2.What can happen to image of an anisotropic sample when you rotate it?
3. 3.What additional piece of equipment is added to a polarizing microscope to control anisotropic behavior? How does it accomplish control?
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Devise a straightforward method that allows you to calculate (a) the speed and (b) the angular momentum of an electron in the nth Bohr orbit. Your expressions should contain the number of the orbit, n, and constants.
Using the formula that you devised, calculate the speed of an electron and the angular momentum of an electron in the tenth Bohr orbit. Units for answers are m/s for speed and J/s for angular momentum.
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Free-body Diagrams - 01
Due in 21 hours, 49 minutes
A free-body diagram is a major tool we use to help analyze problems involving forces. To create a free-body diagram, place a dot on the paper to represent the object (or objects) of interest and then draw all of the forces acting on that body. The force vectors are drawn with their tail on the dot. A major step in any of our force problems is correctly identifying all of the forces acting on an object. There are three possible free-body diagrams shown at the top of the problem. Select the appropriate free-body diagram for each of the situations listed below. If there are two items mentioned, select the free-body diagram for the first object mentioned (book, block, you, ball).
A [One arrow pointing down]
B [One arrow pointing down, on down, one left, one right]
C [One arrow pointing down, one pointing up]
A
B
C
A book is sitting stationary on a table.
A
B
C
A block is being pulled by a string to the right at a
constant speed. There is friction between the block and the
table.
A
B
C
You are standing stationary on a flat floor.
A
B
C
A block is hanging from a string and is not
accelerating.
A
B
C
A ball is flying through the air. Ignore air resistance
(assume projectile motion).
Incorrect. Tries 1/10 Previous Tries
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Find the fundamental frequency and the frequency of the first three overtones of a pipe 55.0 cm long, if the pipe is open at both ends.
Please enter your answer as four numbers, separated with commas.
Find the fundamental frequency and the frequency of the first three overtones of a pipe 55.0 cm long, if the pipe is closed at one end.
Please enter your answer as four numbers, separated with commas.
If the pipe is open at both ends, what is the number of the highest harmonic that may be heard by a person who can hear frequencies from 20.0 Hz to 2.00×104 Hz?
If the pipe is closed at one end, what is the number of the highest harmonic that may be heard by a person who can hear frequencies from 20.0 Hz to 2.00×104 Hz
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A sealed vertical cylinder of radius R and height h = 0.616 m is initially filled halfway with water, and the upper half is filled with air. The air is initially at standard atmospheric pressure, p0 = 1.01·105 Pa. A small valve at the bottom of the cylinder is opened, and water flows out of the cylinder until the reduced pressure of the air in the upper part of the cylinder prevents any further water from escaping. By what distance is the depth of the water lowered? (Assume that the temperature of water and air do not change and that no air leaks into the cylinder.)
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Two stationary positive point charges, charge 1 of magnitude 4.00nC and charge 2 of magnitude 1.70nC , are separated by a distance of 39.0cm . An electron is released from rest at the point midway between the two charges, and it moves along the line connecting the two charges.
What is the speed vfinal of the electron when it is 10.0cm from charge 1?
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A -11.0 nC point charge and a +22.0nC point charge are 18.0 cm apart on the x-axis.
A)What is the electric potential at the point on the x-axis where the electric field is zero?
B) What is the magnitude of the electric field at the point on the x-axis, between the charges, where the electric potential is zero?
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Calculate the effective value of g, the acceleration of gravity, at 7400m above the Earth's surface.
Calculate the effective value of g, the acceleration of gravity, at 7400 km above the Earth's surface.
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