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QveST [7]
3 years ago
8

A pendulum is made by letting a 4 kg mass swing at the end of a string that has a length of 1.5 meter. The maximum angle that th

e string makes with the vertical is 30 degrees (in both directions). What is the change in the potential energy of the mass as it moves from the lowest point to the highest point of its path?
Physics
1 answer:
olga nikolaevna [1]3 years ago
6 0

Answer:

Approximately 7.8\; \rm J.

Explanation:

The change in the gravitational potential energy of the pendulum is directly related to the change in its height.

Refer to the sketch attached. The pendulum is initially at \rm P_2. Its highest point is at P_1. The length of segment \rm BP_2 gives the change in its height.

The lengths of \rm AP_1 and \rm AP_2 are simply the length of the string, 1.5\; \rm m. To find the length of \rm BP_2, start by calculating the length of \rm AB.

\rm AB forms a leg in the right triangle \rm \triangle AP_1B. Besides, it is adjacent to the 30^\circ angle \rm P_1\hat{A}B. Its length would be:

\rm AB = 1.5 \times \cos(30^\circ) \approx 1.30\; \rm m.

The length of \rm BP_2 would thus be

\rm BP_2 = AP_2 - AB = 1.5 - 1.30 \approx 0.20\; \rm m.

The change in gravitational potential energy can be found with the equation

\Delta \mathrm{GPE} = m \cdot g \cdot \Delta h. In this equation,

  • m is the mass of the object,
  • g \approx 9.81\; \rm N \cdot kg^{-1} near the surface of the earth, and
  • \Delta h is the change in the object's height.

In this case, m = 4\; \rm kg and \Delta h \approx 0.20\; \rm m. Therefore:

\Delta \mathrm{GPE} = 4 \times 9.81 \times 0.20 \approx 7.8\; \rm J.

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pishuonlain [190]

I think the answer is A.........

7 0
2 years ago
Calculate the change in length of concrete sidewalk (coefficient of linear expansion for concrete is 12*10^-6/celcius) that is 1
anyanavicka [17]

Answer:

The answer to your question is 5.4 cm

Explanation:

This problem refers to calculate the change in length in one dimension due to a change in temperature.

Data

α = 12 x 10⁻⁶

Lo = 150 meters

ΔT = 30 °C

Formula

                    ΔL/Lo = αΔT

solve for ΔL

                    ΔL = αLoΔT

Substitution

                    ΔL = (12 x 10⁻⁶)(150)(30)

Simplification

                    ΔL = 0054 m = 5.4 cm

7 0
3 years ago
The emf induced in a coil that is rotating in a magnetic field will be at a maximum at which moment?
adelina 88 [10]
TLDR: It will reach a maximum when the angle between the area vector and the magnetic field vector are perpendicular to one another.

This is an example that requires you to investigate the properties that occur in electric generators; for example, hydroelectric dams produce electricity by forcing a coil to rotate in the presence of a magnetic field, generating a current.

To solve this, we need to understand the principles of electromotive forces and Lenz’ Law; changing the magnetic field conditions around anything with this potential causes an induced current in the wire that resists this change. This principle is known as Lenz’ Law, and can be described using equations that are specific to certain situations. For this, we need the two that are useful here:

e = -N•dI/dt; dI = ABcos(theta)

where “e” describes the electromotive force, “N” describes the number of loops in the coil, “dI” describes the change in magnetic flux, “dt” describes the change in time, “A” describes the area vector of the coil (this points perpendicular to the loops, intersecting it in open space), “B” describes the magnetic field vector, and theta describes the angle between the area and mag vectors.

Because the number of loops remains constant and the speed of the coils rotation isn’t up for us to decide, the only thing that can increase or decrease the emf is the change in magnetic flux, represented by ABcos(theta). The magnetic field and the size of the loop are also constant, so all we can control is the angle between the two. To generate the largest emf, we need cos(theta) to be as large as possible. To do this, we can search a graph of cos(theta) for the highest point. This occurs when theta equals 90 degrees, or a right angle. Therefore, the electromotive potential will reach a maximum when the angle between the area vector and the magnetic field vector are perpendicular to one another.

Hope this helps!
6 0
3 years ago
b. A string is wrapped around a pulley of radius 0.05 m and moment of inertia 0.2 kg  m2. If the string is pulled with a force
Oduvanchick [21]

Answer:

f = 8 N

Explanation:

Data provided in the question

Radius of the pulley  = r = 0.05 m

Moment of inertia = (I) = 0.2 kg.m^{2}

Angular acceleration = ∝ = 2 rad/sec

Based on the above information

As we know that

Torque is

= force \times  radius

= f \times r

And,

Torque is also

= moment\ of\ inertia \times angular\ acceleration

= I \times \alpha

So,

We can say that

f \times r = I \times \alpha

f \times 0.05 = 0.2 \times 2

0.05f = 0.4

f = 8 N

We simply applied the above formulas

8 0
3 years ago
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dmitriy555 [2]

The correct answer is C; Bicycles.

Further Explanation:

In major cities, in the United States, have implemented signal lights specifically designed for bicycle riders. The riders also have their own designated bike lanes in many large cities. Drivers in vehicles, are to give the right of way to people on bicycles.

Bicycle riders are to follow the same laws and laws specifically for the riders or they can face fines and tickets.

Learn more about bicycle laws at brainly.com/question/8934107

#LearnwithBrainly

7 0
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