Predict/Calculate A yo-yo moves downward until it reaches the end of its string, where it “sleeps.” As it sleeps—that is, spins in place—its angular speed decreases from 35 rad/s to 25 rad/s. During this time it completes 120 revolutions, (a) How much time did it take for the yo-yo to slow from 35 rad/s to 25 rad/s? (b) How much time does it take for the yo-yo to slow from 25 rad/s to 15 rad/s? Assume a constant angular acceleration as the yo-yo sleeps.
Predict/Calculate A yo-yo moves downward until it reaches the end of its string, where it “sleeps.” As it sleeps—that is, spins in place—its angular speed decreases from 35 rad/s to 25 rad/s. During this time it completes 120 revolutions, (a) How much time did it take for the yo-yo to slow from 35 rad/s to 25 rad/s? (b) How much time does it take for the yo-yo to slow from 25 rad/s to 15 rad/s? Assume a constant angular acceleration as the yo-yo sleeps.
Predict/Calculate A yo-yo moves downward until it reaches the end of its string, where it “sleeps.” As it sleeps—that is, spins in place—its angular speed decreases from 35 rad/s to 25 rad/s. During this time it completes 120 revolutions, (a) How much time did it take for the yo-yo to slow from 35 rad/s to 25 rad/s? (b) How much time does it take for the yo-yo to slow from 25 rad/s to 15 rad/s? Assume a constant angular acceleration as the yo-yo sleeps.
Definition Definition Rate of change of angular velocity. Angular acceleration indicates how fast the angular velocity changes over time. It is a vector quantity and has both magnitude and direction. Magnitude is represented by the length of the vector and direction is represented by the right-hand thumb rule. An angular acceleration vector will be always perpendicular to the plane of rotation. Angular acceleration is generally denoted by the Greek letter α and its SI unit is rad/s 2 .
î
A proton is projected in the positive x direction into a region of uniform electric field E = (-5.50 x 105) i N/C at t = 0. The
proton travels 7.20 cm as it comes to rest.
(a) Determine the acceleration of the proton.
magnitude 5.27e13
direction -X
m/s²
(b) Determine the initial speed of the proton.
8.71e-6
magnitude The electric field is constant, so the force is constant, which means the acceleration will be constant.
m/s
direction +X
(c) Determine the time interval over which the proton comes to rest.
1.65e-7
Review you equations for constant accelerated motion. s
Three charged particles are at the corners of an equilateral triangle as shown in the figure below. (Let q = 2.00 μC, and
L = 0.750 m.)
y
7.00 με
60.0°
L
9
-4.00 μC
x
(a) Calculate the electric field at the position of charge q due to the 7.00-μC and -4.00-μC charges.
112
Once you calculate the magnitude of the field contribution from each charge you need to add these as vectors.
KN/CI + 64
×
Think carefully about the direction of the field due to the 7.00-μC charge. KN/Cĵ
(b) Use your answer to part (a) to determine the force on charge q.
240.0
If you know the electric field at a particular point, how do you find the force that acts on a charge at that point? mN
Î + 194.0
×
If you know the electric field at a particular point, how do you find the force that acts on a charge at that point? mN
In the Donkey Kong Country video games you often get around by shooting yourself out of barrel cannons. Donkey Kong wants to launch out of one barrel and land in a different one that is a distance in x of 9.28 m away. To do so he launches himself at a velocity of 22.6 m/s at an angle of 30.0°. At what height does the 2nd barrel need to be for Donkey Kong to land in it? (measure from the height of barrel 1, aka y0=0)
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.