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jeka94
3 years ago
10

The current through a certain heater wire is found to be fairly independent of its temperature. If the current through the heate

r wire is doubled, the amount of energy delivered by the heater in a given time interval will(a) increase by a factor of two. (b) decrease by a factor of two. (c) increase by a factor of four.(d) decrease by a factor of four. (e) increase by a factor of eight.
Physics
1 answer:
irina [24]3 years ago
5 0

Answer:

(c) increase by a factor of four

Explanation:

energy = power x time, and power = resistance x current ^2. 2^2 = 4.

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1. A hydraulic lift is to be used to lift a truck masses 5000 kg. If the diameter of the
zheka24 [161]

Answer:

a)   F = 4.9 10⁴ N,  b)   F₁ = 122.5 N

Explanation:

To solve this problem we use that the pressure is transmitted throughout the entire fluid, being the same for the same height

1) pressure is defined by the relation

           P = F / A

to lift the weight of the truck the force of the piston must be equal to the weight of the truck

          ∑F = 0

          F-W = 0

          F = W = mg

          F = 5000 9.8

          F = 4.9 10⁴ N

the area of ​​the pisto is

          A = pi r²

          A = pi d² / 4

          A = pi 1 ^ 2/4

          A = 0.7854 m²

pressure is

          P = 4.9 104 / 0.7854

          P = 3.85 104 Pa

2) Let's find a point with the same height on the two pistons, the pressure is the same

          \frac{F_1}{A_1} = \frac{F_2}{A_2}

where subscript 1 is for the small piston and subscript 2 is for the large piston

          F₁ = \frac{A_1}{A_2} \ F_2

the force applied must be equal to the weight of the truck

          F₁ = ( \frac{d_1}{d_2} )^2\  m g

          F₁ = (0.05 / 1) ² 5000 9.8

          F₁ = 122.5 N

7 0
3 years ago
4 This question has several parts that must be completed sequentially. If you skip a part of the question, you will not receive
zubka84 [21]

Answer:at 21.6 min they were separated by 12 km

Explanation:

We can consider the next diagram

B2------15km/h------->Dock

|

|

B1 at 20km/h

|

|

V

So by the time B1 leaves, being B2 traveling at constant 15km/h and getting to the dock one hour later means it was at 15km from the dock, the other boat, B1 is at a distance at a given time, considering constant speed of 20km/h*t going south, where t is in hours, meanwhile from the dock the B2 is at a distance of (15km-15km/h*t), t=0, when it is 8pm.

Then we have a right triangle and the distance from boat B1 to boat B2, can be measured as the square root of (15-15*t)^2 +(20*t)^2. We are looking for a minimum, then we have to find the derivative with respect to t. This is 5*(25*t-9)/(sqrt(25*t^2-18*t+9)), this derivative is zero at t=9/25=0,36 h = 21.6 min, now to be sure it is a minimum we apply the second derivative criteria that states that if the second derivative at the given critical point is positive it means here we have a minimum, and by calculating the second derivative we find it is 720/(25 t^2 - 18 t + 9)^(3/2) that is positive at t=9/25, then we have our answer. And besides replacing the value of t we get the distance is 12 km.

3 0
3 years ago
A generator uses a coil that has 100 turns and a 0.50-T magnetic field. The frequency of this generator is 60.0 Hz, and its emf
lana [24]

Answer:

38 m

Explanation:

Number of turns=N=100

Magnetic field=B=0.50 T

Frequency of the generator=f=60 Hz

Rms value of emf=E_{rms}=120 V

We have to find the length of the wire from which the coil is made.

Peak value of emf=E_0=E_{rms}\sqrt 2=120\times \sqrt 2=169.7 V

Length of wire=4\sqrt{\frac{NE_0}{2\pi fB}}

Substitute the values

Length of wire=4\times \sqrt{\frac{169.7\times 100}{0.50\times 2\pi\times 60}}

Length of wire=38 m

Hence, the length of wire from which the coil is made=38 m

6 0
3 years ago
From this diagram which of the following can you conclude
Volgvan

Answer: A

Explanation:

I say opposites attract

3 0
3 years ago
Read 2 more answers
Two astronauts of mass 100 kg are 2 m apart in outer space. What is the
fredd [130]

The force of gravity between the astronauts is 1.67\cdot 10^{-7}N

Explanation:

The magnitude of the gravitational force between two objects is given by:

F=G\frac{m_1 m_2}{r^2}

where :

G=6.67\cdot 10^{-11} m^3 kg^{-1}s^{-2} is the gravitational constant

m_1, m_2 are the masses of the two objects

r is the separation between them

In this problem, we have two astronauts, whose masses are:

m_1 = 100 kg\\m_2 = 100 kg

While the separation between the astronauts is

r = 2 m

Substituting into the equation, we can find the gravitational force between the two astronauts:

F=\frac{(6.67\cdot 10^{-11})(100)(100)}{2^2}=1.67\cdot 10^{-7}N

Learn more about gravitational force:

brainly.com/question/1724648

brainly.com/question/12785992

#LearnwithBrainly

4 0
3 years ago
Read 2 more answers
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