Use this fact together with Equations (1) and (2):
(3) a = Rα =
TR2 |
I |
=
mg − T |
m |
Solve for the tension T:
(4) 3.52
Substitute Equation (4) into Equation (2) and solve for a:
(5) 2
Use a = Rα and Equation (5) to solve for α:
3
MASTER IT HINTS: GETTING STARTED | I'M STUCK!
Suppose the wheel is rotated at a constant rate so that the mass
has an upward speed of 4.52 m/s when it reaches a point P.
At that moment, the wheel is released to rotate on its own. It
starts slowing down and eventually reverses its direction due to
the downward tension of the cord. What is the maximum height,
h, the mass will rise above the point P?
h =
In: Physics
When an object is placed at the proper distance to the left of a converging lens, the image is focused on a screen 31.0 cmto the right of the lens. A diverging lens is now placed 14.2 cm to the right of the converging lens, and it is found that the screen must be moved 19.5 cm farther to the right to obtain a sharp image.
What is the focal length of the diverging lens?
......... cm
In: Physics
A student sits on a rotating stool holding two 3.2-kg objects. When his arms are extended horizontally, the objects are 1.0 m from the axis of rotation and he rotates with an angular speed of 0.75 rad/s. The moment of inertia of the student plus stool is 3.0 kg · m2 and is assumed to be constant. The student then pulls in the objects horizontally to 0.36 m from the rotation axis.
(a) Find the new angular speed of the student. rad/s
(b) Find the kinetic energy of the student before and after the objects are pulled in. before & after (J)
In: Physics
A raft is made of 18 logs lashed together. Each is 29.0 cm in diameter and has a length of 7.00 m. How many people (whole number) can the raft hold before they start getting their feet wet, assuming the average person has a mass of 72.0 kg? Do not neglect the weight of the logs. Assume the density of wood is 600 kg/m³
In: Physics
An electron jumps from the 4th orbit into 3rd orbit of 3Li7. Find the following (i) radii of both orbits (ii) Energies of both orbits (iii) wavelength and frequency of photon emitted as a result of this transition. Please show detailed work so I can understand how it is done.
In: Physics
Magnetic field strength decreases as you get farther from the poles. Does the flux through the face of the coil change as you move the magnet? Explain your reasoning.
Why does the needle of the Galvanometer deflect when you bring a magnet in close to the coil? Is the deflection in accordance with Lenz's Law? Justify your answer in terms of Lenz's Law and your answer above.
In: Physics
What happens if you perform a double slit experiment near an event horizon, if one of the slits is outside, one is inside the event horizon?
In: Physics
At an intersection, a car is driving through a turn with an effective radius 64 ft. The coefficients of kinetic and static friction are 0.4 and 0.7, respectively. Derive an expression for the maximum speed at which the car can drive through this turn.
The set up Newton's Law and find the answer. Eventually evaluate your answer.
Below answer with the speed in mph (use mph as units).
In: Physics
A power line 50km long has a total resistance of 0.60ohm. A generator produces 100V at 70A. in order to reduce energy loss due to heating of the transmission line, the voltage is stepped up with a transformer with a primary to secondary turns ratio of 1 to 100. What percentage of the original energy is lost when the transformer is not used?
In: Physics
Two capacitors are identical, except that one is empty and the other is filled with a dielectric (κ = 4.69). The empty capacitor is connected to a 11.0-V battery. What must be the potential difference across the plates of the capacitor filled with a dielectric so that it stores the same amount of electrical energy as the empty capacitor?
In: Physics
A particle of mass 5.00 kg is attached to a spring with a force
constant of 210 N/m. It is oscillating on a frictionless,
horizontal surface with an amplitude of 4.00 m. A 8.00-kg object is
dropped vertically on top of the 5.00-kg object as it passes
through its equilibrium point. The two objects stick
together.
(a) What is the new amplitude of the vibrating system after the
collision?_______________
(b) By what factor has the period of the system
changed?______________
(c) By how much does the energy of the system change as a result of
the collision?____________J
In: Physics
A red ball is thrown down with an initial speed of 1.3 m/s from a height of 27 meters above the ground. Then, 0.5 seconds after the red ball is thrown, a blue ball is thrown upward with an initial speed of 24 m/s, from a height of 0.8 meters above the ground. The force of gravity due to the earth results in the balls each having a constant downward acceleration of 9.81 m/s2
What is the speed of the red ball right before it hits the ground?
(Is it just jus the velocity equestion?)
How long after the red ball is thrown are the two balls in the air at the same height?
Maybe I am not doing something right, but this is what I have:
27 - 1.3t - 4.9t^2 = -4.9t^2 + 28.9t-12.425
with -4.9t^2 + 28.9t-12.425 being derived from .8 +
24(t-.5)-4.9(t-.5)^2 the only thing I can thing of would be to
maybe to have it as 8 + 24(t+.5)-4.9(t+.5)^2 ?
Is the acceleration postive or negative and is speeding up or slowing down?
In: Physics
Using Stefan-Boltzmann and Wien laws
The Sun emits P = 4 1026Watts, its radius is 6.95 10 ^89m and its surface temperature T(Sun) = 5,800 K. We know that the Sun will gradually increase its power output in the future. We also know that its surface temperature will not change significantly, at least for a while. Using the law for the ‘black body’ radiation, find how much the Sun’s radius will change in %, if the power output of the Sun doubles.
In: Physics
An AC generator supplies an rms voltage of 115 V at 60.0 Hz. It is connected in series with a 0.550 H inductor, a 3.90 μF capacitor and a 311 Ω resistor. What is the impedance of the circuit?
What is the rms current through the resistor?
What is the average power dissipated in the circuit?
What is the peak current through the resistor?
What is the peak voltage across the inductor?
What is the peak voltage across the capacitor?
The generator frequency is now changed so that the circuit is in resonance. What is that new (resonance) frequency?
In: Physics
Make an experiment and answer the question below: 1. Place the can on its side on a flat smooth surface like a table or a smooth floor. 2. Rub the blown-up balloon back and forth through your hair really fast. 3. Now the fun part – Hold the balloon close to the can without actually touching the can. The can will start to roll towards the balloon without you even touching it! Try This Too: While you’ve got the balloon out, tear up part of tissue into tiny pieces about 1/4 inch (.5 cm) big. Rub the balloon on your hair again and bring it close to the tissue pieces. They will be attracted to the balloon and then jump away. When you rub the balloon through your hair, invisible electrons (with a negative charge) build up on the surface of the balloon. This is called static electricity, which means “non-moving electricity” The electrons have the power to pull very light objects (with a positive charge) toward them – like the soda can. to answer these questions: 1. Does the size of the balloon change the power of the pull? 2. Does the length of the person's hair affect the power of static electricity? 3. How much water can you put in the can until the balloon can’t pull it anymore?
In: Physics