How many dollars the beef industry contribute to the us economy

In what ways is thermal energy transferred during physical and chemical changes

Sphinxa [80]

Explanation:

chemical changes

>produce new substances w/ different chemical structure/ properties

> thermal energy can be used to BREAK bonds (endothermic)

>thermal energy can be transferred to a chem rxn to help form new products (endothermic)

> heat can be released by an exothermic chemical reaction (excess energy- the total energy used to break bonds is less than energy released in forming new bonds)

physical changes

>does not result in new substances (typically changes in state- solid, liquid, gas)

> thermal energy can be transferred to EVAPORATE water (add thermal E... water (liquid) to steam (gas)) or FREEZE water (remove thermal E... water (liquid) to ice (solid))

3 0

3 years ago

Compare and contrast the electric force with the gravitational force

Olenka [21]

Similarities:

- The gravitational force and the electric force have a similar form.

In fact, gravitational force is given by:

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

where G is the gravitational constant, m1 and m2 are the masses of the two objects, r is the separation between the two objects.

The electric force is given by:

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

where k is the Coulomb constant, q1 and q2 are the charges of the two objects, r is the separation between the two objects.

As we see, the two forces have same dependency on the distance (inversely proportional to the square of the distance)

- Both forces are non-contact forces: this means that in both cases, the two objects do not to be in contact with each other, because the force is still acting from a distance also.

Differencies:

- The gravitational force is attractive only; on the contrary, the electric force can be either attractive or repulsive, depending on the relative sign of the two charges. In fact, when the two charges have same sign, the force is repulsive; when the two charges have opposite sign, the force is attractive.

- The gravitational force is much weaker than the electric force. This can be seen by comparing the value of the constant in the two formulas; we have:

$G=6.67\cdot 10^{-11} m^3 kg^{-1}s^{-2}$ for the gravitational force

$k=8.99 \cdot 10^9 Nm^2C^{-2}$ for the electric force

As we see, the electric force is much stronger than the gravitational force.

6 0

3 years ago

If you're driving towards the sun late in the afternoon, you can reduce the glare from the road by wearing sunglasses that permi

zubka84 [21]

The answer is A. Polarized in a vertical plane

If positioned correctly, a polarized lenses can block all reflected light from horizontal surface such as road

8 0

3 years ago

Read 2 more answers

A student pushes a 10 kg box with a force of 30 N at an angle 45 degrees below the horizontal . The box experi 21.2 N of force a

Shkiper50 [21]

Answer:

Acceleration =0

Explanation:

There are two forces on the box in horizontal direction.

First one is horizontal component of 30N at 45°.

$F=\frac{1}{\sqrt{2} }*30=21.2$

Another one is given in opposite to direction of motion mean opposite to this force.

Which is = 2.22 N

Now we know F (net) =mass*acceleration(center of mass)

21.2-21.2 =10*acceleration

acceleration =0

6 0

4 years ago

An iv curve is generated for two ohmic devices, one is a good conductor and the other is a good insulator. which one will have a

allochka39001 [22]

As per the question there are two ohmic devices.

The first ohmic device is a good conductor and the second one is a good insulator.

As per Ohm's law the current flowing through a conductor is directly proportional to the potential difference maintained across the two ends of a conductor at constant temperature and pressure. If V is the potential and I is the current flow through these Ohmic devices,then mathematically it can be written as-

V∝ I [ at constant temperature and pressure]

⇒V= IR

Here R is the proportionality constant called resistance of the material.

Hence the resistance R is calculated as -

$R=\frac{V}{I}$

Now a graph is plotted taking potential V on X-axis and current I along Y- axis.

The graph will be a straight line for conductor and will be a curve depending on the type of insulator.

The slope of this graph will give the resistance of the material.

An insulator is a substance through which current flow is very low as its resistance is very high.Hence the slope of the V-I curve is very large.

A conductor is that substance through which current is flown easily as the resistance of conductor is very low.Hence the slope of V-I curve is smaller,

5 0

3 years ago