answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
MissTica
2 years ago
11

The energy of a certain charged capacitor is 7 J. What is the new energy stored in that capacitor if its charge is decreased to

1 / 4 of its original value (imagine allowing some of the charge to move through a resistor)? Remember that the capacitance, C , that relates Q and V is unchanged.
Enew=?
Physics
1 answer:
poizon [28]2 years ago
6 0

Answer:

The new energy is 1/16 of the original energy

Explanation:

A capacitor is an electric device which is able to store charge when it is connected to a power supply.

The energy stored in a capacitor is given by the equation

E=\frac{Q}{2C}

where:

Q is the charge stored on the capacitor

C is the capacitance of the capacitor

For the capacitor in this problem, initially we have

E = 7 J (energy) when the charge stored is Q and the capacitance is C

Later, the charge is decreased to 1/4 of its original value, so the new charge is

Q'=\frac{1}{4}Q

Since the capacitance remains the same, the new energy is

E'=\frac{(\frac{1}{4}Q)^2}{2C}=\frac{1}{16}\frac{Q^2}{2C}=\frac{1}{16}E

Therefore, the new energy is 1/16 of the original energy.

You might be interested in
You testify as an expert witness in a case involving an accident in which car A slid into the rear of car B, which was stopped a
bekas [8.4K]

Answer:

A) 12.08 m/s

B) 19.39 m/s

Explanation:

A) Down the hill, we will apply Newton’s second law of motion in the downward direction to get:

mg(sinθ) – F_k = ma

Where; F_k is frictional force due to kinetic friction given by the formula;

F_k = (μ_k) × F_n

F_n is normal force given by mgcosθ

Thus;

F_k = μ_k(mg cosθ)

We now have;

mg(sinθ) – μ_k(mg cosθ) = ma

Dividing through by m to get;

g(sinθ) – μ_k(g cosθ) = a

a = 9.8(sin 12.03) - 0.6(9.8 × cos 12.03)

a = -3.71 m/s²

We are told that distance d = 24.0 m and v_o = 18 m/s

Using newton's 3rd equation of motion, we have;

v = √(v_o² + 2ad)

v = √(18² + (2 × -3.71 × 24))

v = 12.08 m/s

B) Now, μ_k = 0.10

Thus;

a = 9.8(sin 12.03) - 0.1(9.8 × cos 12.03)

a = 1.08 m/s²

Using newton's 3rd equation of motion, we have;

v = √(v_o + 2ad)

v = √(18² + (2 × 1.08 × 24))

v = 19.39 m/s

6 0
2 years ago
Can light cause the rubber to become solid? Why or why not? Does it matter what type of light she shines on the rubber?
ELEN [110]

Answer:

Yes, ultraviolet light can turn a rubber into solid due to prolong exposure.

Explanation:

A rubber is a material with an elastic property, causing it to be deform by an external force but takes its shape when the force is removed. Light is an electromagnetic wave which causes the sensation of vision. It transfers energy to a medium during propagation through the medium.

Generally, most light do not cause hardness of a rubber. But an ultraviolet light can cause rubber to become solid over a period of time. This is possible if there is a prolong exposure of the rubber, and because of the evaporation of volatiles in the polymer material. Ultraviolet light are known to cause a rubber to become solid.

8 0
2 years ago
If the force of gravity between a book of mass 0.50 kg and a calculator of 0.100 kg is 1.5 × 10-10 N, how far apart are they?  (
valkas [14]
The gravitational force between two masses m₁ and m₂ is
F=G \frac{m_{1} m_{2}}{d^{2}}
where
G = 6.67408 x 10⁻¹¹ m³/(kg-s²), the gravitational constant
d =  distance between the masses.

Given:
F = 1.5 x 10⁻¹⁰ N
m₁ = 0.50 kg
m₂ = 0.1 kg

Therefore
1.5 x 10⁻¹⁰ N = (6.67408 x 10⁻¹¹ m³/(kg-s²))*[(0.5*0.1)/(d m)²]
d² = [(6.67408x10⁻¹¹)*(0.5*0.1)]/1.5x10⁻¹⁰
     = 0.0222
d = 0.1492 m = 149.2 mm

Answer: 149.2 mm
8 0
2 years ago
With your hand parallel to the floor and your palm upright, you lower a 3-kg book downward. If the force exerted on the book by
Stells [14]
For Newton's second law, the resultant of the forces acting on the book is equal to the product between the mass of the book and its acceleration:
\sum F = ma (1)

There are only two forces acting on the book:
- its weight, directed downward: mg
- the force exerted by the hand on the book, of 20 N, directed upward

so, equation (1) becomes
mg - F = ma
from which we can calculate the book's acceleration, a:
a= g -  \frac{F}{m}= 9.81 m/s^2 - \frac{20 N}{3 kg}=3.14 m/s^2
7 0
2 years ago
Read 2 more answers
A na+ ion moves from inside a cell, where the electric potential is -72 mv, to outside the cell, where the potential is 0 v. wha
Vlada [557]
The change in electric potential energy of the ion is equal to the charge multiplied by the voltage difference:
\Delta U = q \Delta V = q (V_f - V_i)
where the charge q of the na+ ion is equal to one positive charge, so it's equal to the proton charge: q=1.6 \cdot 10^{-19} C, and Vf and Vi are the final and initial voltages.

Substituting the numbers, we find:
\Delta U = (1.6 \cdot 10^{-19}C)(0 V-(-0.072 V))=1.15 \cdot 10^{-20} J
7 0
2 years ago
Read 2 more answers
Other questions:
  • Bob has a brother, jim, who has a daughter named bertha. Bertha's daughter, jennifer, has a sister named penny. which of the fol
    5·2 answers
  • Monitoring systems may also use ____, which are devices that respond to a stimulus (such as heat, light, or pressure) and genera
    15·1 answer
  • You throw a beanbag in the air and catch it 2.2 s later at the same place at which you threw it. How high did it go? What was th
    9·1 answer
  • A 2 kg bar of metal weighs about 4.4 pounds. Approximately how much does it weigh in newtons?
    10·2 answers
  • Two blocks a and b ($m_a>m_b$) are pushed for a certain distance along a frictionless surface. how does the magnitude of the
    7·1 answer
  • Hanging by a thread. Two metal spheres hang from nylon threads and attract each other when brought close together. (i) What can
    13·1 answer
  • When Earth’s Northern Hemisphere is tilted toward the Sun during June, some would argue that the cause of our seasons is that th
    5·1 answer
  • A heavy turntable, used for rotating large objects, is a solid cylindrical wheel that can rotate about its central axle with neg
    10·1 answer
  • The wad of clay of mass m = 0.36 kg is initially moving with a horizontal velocity v1 = 6.0 m/s when it strikes and sticks to th
    7·1 answer
  • Rod A has twice the diameter of rod B, but both are made of iron and have the same initial length. Both rods are now subjected t
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!