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2 years ago

A wagon is accelerating down a hill. Which statement is true?

1 answer:

3 0

Potential energy decreases and kinetic energy increases.

Potential energy is related to the height, since the wagon is going downhill, height decreases and potential energy decreases.

Kinetic energy is related to the speed, since the wagon is speeding up, kinetic energy increases.

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The magnitude J(r) of the current density in a certain cylindrical wire is given as a function of radial distance from the cente

kipiarov [429]

Answer:

$I=68.31\times 10^{-6}\ A$

Explanation:

Given that

J(r) = Br

We know that area of small element

dA = 2 π dr

I = J A

dI = J dA

Now by putting the values

dI = B r . 2 π dr

dI= 2π Br² dr

Now by integrating above equation

$\int_{0}^{I}dI= \int_{r_1}^{r_2}2\pi Br^2 dr$

$I={2\pi B}\times \dfrac{r_2^3-r_1^3}{3}$

Given that

B= 2.35 x 10⁵ A/m³

r₁ = 2 mm

r₂ = 2+ 0.0115 mm

r₂ = 2.0115 mm

$I={2\pi B}\times \dfrac{r_2^3-r_1^3}{3}$

By putting the values

$I={2\pi \times 2.35 \times 10^5 }\times \dfrac{(2.0115\times 10^{-3})^3-(2\times 10^{-3})^3}{3}\ A$

$I=68.31\times 10^{-6}\ A$

7 0

2 years ago

Read 2 more answers

An athlete stretches a spring an extra 40.0 cm beyond its initial length. how much energy has he transferred to the spring, if t

marissa [1.9K]

The energy transferred to the spring is given by:
$U= \frac{1}{2}kx^2$
where
k is the spring constant
x is the elongation of the spring with respect its initial length

Let's convert the data into the SI units:
$k=52.9 N/cm = 5290 N/m$
$x=40.0 cm=0.4 m$

so now we can use these data inside the equation ,to find the energy transferred to the spring:
$U= \frac{1}{2}kx^2= \frac{1}{2}(5290 N/m)(0.4m)^2=423.2 J$

4 0

2 years ago

Which of the following statements best describes the characteristic of the restoring force in the spring-mass system described i

Grace [21]

Answer : The restoring force is directly proportional to the displacement of the block.

Explanation :

Restoring force is defined as the force that is exerted by the spring due to its mass.

Mathematically, the restoring force can be written as :

$F\propto-x$

F = - k x

where,

k is the spring constant.

x is the displacement caused due to the mass.

Negative sign shows that the force is acting in opposite direction.

So, it is clear that the restoring force is directly proportional to the displacement of the block.

Hence, the correct option is (b) " The restoring force is directly proportional to the displacement of the block ".

5 0

2 years ago

Read 2 more answers

Listed following are three possible models for the long-term expansion (and possible contraction) of the universe in the absence

Lynna [10]

Answer:

1) Recollapsing universe

2) critical universe

3) Coasting universe

Explanation:

According to the smallest ration (ratio actual mass density to current density) to largest ration, rank of models for expansion of universe are

1) Recollapsing universe -in this, metric expansion of space is reverse and universe recollapses.

2) critical universe - in this, expansion of universe is very low.

3) Coasting universe - in this, expansion of universe is steady and uniform

6 0

2 years ago

What is the final temperature when a 3.0 kg gold bar at 99 0C is dropped into 0.22 kg of water at 25oC?

slavikrds [6]

I will post my work, but is that 99 degrees Celsius and 25 degrees Celsius?

All you have to do is plug in the initial temperature for gold where it says Tg and the initial temperature for the water where it says Tw and then plug that in and you will have your answer.

8 0

2 years ago