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3 years ago

What happens to a bar of metal when its heated?

Physics

2 answers:

Nookie1986 [14]3 years ago

5 0

Metal expands when heated.

SashulF [63]3 years ago

5 0

Answer:

It gets longer when heated.

Explanation:

If the temperature of a solid is increased, the solid expands. When a solid is cooled, it contracts.

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When riding a 10-speed bicycle up a hill, a cyclist shifts the chain to a larger-diameter gear attached to the back wheel. Why i

dimaraw [331]

To solve this problem we will use the concepts of the moment of rotational inertia, angular acceleration and the expression of angular velocity.

The rotational inertia is expressed as follows:

$I = \sum mr^2$

Here,

m = Mass of the object

r = Distance from the rotational axis

The rotational acceleration in terms of translational acceleration is

$\alpha = \frac{a}{R}$

Here,

a = Acceleration

R = Radius of the circular path of the object

The expression for the rotational speed of the object is

$\omega = \frac{\Delta \theta}{\Delta t}$

Here,

$\Delta \theta$ is the angular displacement of the object

The explanation by which when climbing a mountain uphill is changed to a larger pinion, is because it produces a greater torque but it is necessary to make more pedaling to be able to travel the same distance. Basically every turn results in less rotations of the rear wheel. Said energy that was previously used to move the rotation of the wheel is now distributed in more turns of the pedal. Therefore option a and c are correct.

This would indicate that the correct option is D.

8 0

4 years ago

when their center-to-center separation is 50 cm. The spheres are then connected by a thin conducting wire. When the wire is remo

Lera25 [3.4K]

Answer:

q1 = 7.6uC , -2.3 uC

q2 = 7.6uC , -2.3 uC

( q1 , q2 ) = ( 7.6 uC , -2.3 uC ) OR ( -2.3 uC , 7.6 uC )

Explanation:

Solution:-

- We have two stationary identical conducting spheres with initial charges ( q1 and q2 ). Such that the force of attraction between them was F = 0.6286 N.

- To model the electrostatic force ( F ) between two stationary charged objects we can apply the Coulomb's Law, which states:

$F = k\frac{|q_1|.|q_2|}{r^2}$

Where,

k: The coulomb's constant = 8.99*10^9

- Coulomb's law assume the objects as point charges with separation or ( r ) from center to center.

- We can apply the assumption and approximate the spheres as point charges under the basis that charge is uniformly distributed over and inside the sphere.

- Therefore, the force of attraction between the spheres would be:

$\frac{F}{k}*r^2 =| q_1|.|q_2| \\\\\frac{0.6286}{8.99*10^9}*(0.5)^2 = | q_1|.|q_2| \\\\ | q_1|.|q_2| = 1.74805 * 10^-^1^1$ ... Eq 1

- Once, we connect the two spheres with a conducting wire the charges redistribute themselves until the charges on both sphere are equal ( q' ). This is the point when the re-distribution is complete ( current stops in the wire).

- We will apply the principle of conservation of charges. As charge is neither destroyed nor created. Therefore,

$q' + q' = q_1 + q_2\\\\q' = \frac{q_1 + q_2}{2}$

- Once the conducting wire is connected. The spheres at the same distance of ( r = 0.5m) repel one another. We will again apply the Coulombs Law as follows for the force of repulsion (F = 0.2525 N ) as follows:

$\frac{F}{k}*r^2 = (\frac{q_1 + q_2}{2})^2\\\\\sqrt{\frac{0.2525}{8.99*10^9}*0.5^2} = \frac{q_1 + q_2}{2}\\\\2.64985*10^-^6 = \frac{q_1 + q_2}{2}\\\\q_1 + q_2 = 5.29969*10^-^6$ .. Eq2

- We have two equations with two unknowns. We can solve them simultaneously to solve for initial charges ( q1 and q2 ) as follows:

$-\frac{1.74805*10^-^1^1}{q_2} + q_2 = 5.29969*10^-^6 \\\\q^2_2 - (5.29969*10^-^6)q_2 - 1.74805*10^-^1^1 = 0\\\\q_2 = 0.0000075998, -0.000002300123$

$q_1 = -\frac{1.74805*10^-^1^1}{-0.0000075998} = -2.3001uC\\\\q_1 = \frac{1.74805*10^-^1^1}{0.000002300123} = 7.59982uC\\$

6 0

4 years ago

A motorcyclist traveling due north at 50km/h. the wind appears to come from north west at 60km/h . what is the true velocity of

pav-90 [236]

Answer:

6o km/h wind - cyclist wind 50 km/h = 10 km/h Head-Wind.

At NW (45 deg) True wind vel = 10 / (cos 45) = 14.1 km/h.

Explanation:

6 0

3 years ago

Marco is looking for a used sports car,

aksik [14]

Answer:

Explanation:

6 0

3 years ago

Jim climbs up a rope from an initial height of 1.30 m to a final height of 3.20 m. If Jim's mass is 45 kg, what is the change in

vladimir1956 [14]

The change in the gravitational potential energy of the boy is 838 J.

So the correct choice is 838 J.

What is gravitational potential energy?

The energy possessed by an object due to its position from the chosen reference point when gravity is acting on that object is called gravitational potential energy.

The formula to calculate the difference in the potential energy is given by the formula,

U=m*g*h

where U is the difference in the potential energy, m is the mass, g is the acceleration due to gravity, and h is the height difference between the initial height and the final height.

The height difference is given by the formula,

h=h2-h1

where h2 is the final height and h1 is the initial height.

Given that the initial height is 1.30 m and the final height is 3.20 m, substitute h1=1.30 m and h2=3.20 m in the formula of height to calculate the height difference.

h=3.20-1.30

h=1.90 m

The mass of the boy is 45 kg and the value of g is 9.8 m/s^2. Substitute m=45 kg, g=9.8 m/s^2, and h=1.90 m in the formula of the gravitational potential energy to calculate the difference in the gravitational potential energy.

U=45*9.8*1.90

U=837.9 J

U≈838

Learn more about the gravitational potential energy:

brainly.com/question/16155035

#SPJ4

7 0

2 years ago