Which is an example of a way that

Why do scientists believe that dark matter exists even though it cannot be seen?

poizon [28]

Because although they cannot see it, they can see it's influence on objects that can be seen, and it's effects.

3 0

3 years ago

Put the waves in order from shortest to longest wavelength

FromTheMoon [43]

Answer:

b, a, c

Explanation:

The middle one has the shortest wavelength, then it's the top one and the last one has the longest wavelength.

3 0

3 years ago

A boy is trying to roll a bowling ball up a hill, as shown in the image below. If

kherson [118]

The minimum initial velocity that the ball must have for it to reach the top of the hill is 21 m/s. The correct option is D.

<h3>What is mechanical energy?</h3>

The mechanical energy is the sum of kinetic energy and the potential energy of an object at any instant of time.

M.E = KE +PE

A boy is trying to roll a bowling ball up a hill. The friction is ignored. The ball must have to reach the top of the hill with a velocity. The acceleration due to gravity, g = 9.8 m/s²

The conservation of energy principle states that total mechanical energy remains conserved in all situations where there is no external force acting on the system.

M.E bottom of hill = M.E on top of hill

Kinetic energy + Potential energy = Kinetic energy + Potential energy

1/2 mu² + 0 = 0 + mgh

At the top of hill, the velocity will become zero. So, final kinetic energy is zero.

Substituting the values, we have

1/2 x u² = 9.8 x 22.5

u = sqrt [2 x9.8 x 22.5 ]

u= 21 m/s

Thus, the minimum initial velocity that the ball must have for it to reach the top of the hill is 21 m/s.

Learn more about mechanical energy.

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4 0

2 years ago

Two long, parallel wires separated by 3.50 cm carry currents in opposite directions. The current in one wire is 1.55 A, and the

vaieri [72.5K]

Answer:

Therefore,

The magnitude of the force per unit length that one wire exerts on the other is

$\dfrac{F}{l}=2.79\times 10^{-5}\ N/m$

Explanation:

Given:

Two long, parallel wires separated by a distance,

d = 3.50 cm = 0.035 meter

Currents,

$I_{1}=1.55\ A\\I_{2}=3.15\ A$

To Find:

Magnitude of the force per unit length that one wire exerts on the other,

$\dfrac{F}{l}=?$

Solution:

Magnitude of the force per unit length on each of @ parallel wires seperated by the distance d and carrying currents I₁ and I₂ is given by,

$\dfrac{F}{l}=\dfrac{\mu_{0}\times I_{1}\times I_{2}}{2\pi\times d}$

where,

$\mu_{0}=permeability\ of\ free\ space =4\pi\times 10^{-7}$

Substituting the values we get

$\dfrac{F}{l}=\dfrac{4\pi\times 10^{-7}\times 1.55\times 3.15}{2\pi\times 0.035}$

$\dfrac{F}{l}=2.79\times 10^{-5}\ N/m$

Therefore,

The magnitude of the force per unit length that one wire exerts on the other is

$\dfrac{F}{l}=2.79\times 10^{-5}\ N/m$

7 0

3 years ago

Read 2 more answers

A straight wire of length 0.53 m carries a conventional current of 0.2 amperes. What is the magnitude of the magnetic field made

olga55 [171]

Explanation:

It is given that,

Length of wire, l = 0.53 m

Current, I = 0.2 A

(1.) Approximate formula:

We need to find the magnitude of the magnetic field made by the current at a location 2.0 cm from the wire, r = 2 cm = 0.02 m

The formula for magnetic field at some distance from the wire is given by :

$B=\dfrac{\mu_oI}{2\pi r}$

$B=\dfrac{4\pi \times 10^{-7}\times 0.2\ A}{2\pi \times 0.02\ m}$

B = 0.000002 T

$B=10^{-5}\ T$

(2) Exact formula:

$B=\dfrac{\mu_oI}{2\pi r}\dfrac{l}{\sqrt{l^2+4r^2} }$

$B=\dfrac{\mu_o\times 0.2\ A}{2\pi \times 0.02\ m}\times \dfrac{0.53\ m}{\sqrt{(0.53\ m)^2+4(0.02\ m)^2} }$

B = 0.00000199 T

or

B = 0.000002 T

Hence, this is the required solution.

4 0

3 years ago