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2 years ago

How many calories are released when 6 grams of 100°C steam turns to 0°C ice?

Physics

1 answer:

maks197457 [2]2 years ago

6 0

Answer: 4276.2 calories

Explanation:

Given

mass of steam is 6 gm at $100^{\circ}C$

Conversion of steam to ice involves

steam to water at $100^{\circ}C$

water at $100^{\circ}C$ to water at $0^{\circ}C$

water to the ice at $0^{\circ}C$

Calories released during the conversion of steam to water at $100^{\circ}C$

$E_1=mL_v\quad [L_v=\text{latent heat of vaporisation}]\\E_1=6\times 533=3198\ cal.$

Calories released during the conversion of water at $100^{\circ}C$ to water at $0^{\circ}C$

$E_2=mc(\Delta T)\quad [c=\text{specific heat of water,}1\ cal./gm.^{\circ}C]\\E_2=6\times 1\times 100=600\ cal.$

Calories released during the conversion of water to the ice at $0^{\circ}C$

$E_3=mL_f\quad [L_f=\text{latent heat of fusion}]\\E_3=6\times 79.7=478.2\ cal.$

The total energy released is

$E=E_1+E_2+E_3\\E=3198+600+478.2=4276.2\ cal.$

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In a simple harmonic motion, when the displacement from the equilibrium position is at its maximum,

Keith_Richards [23]

Answer:

option B

Explanation:

The correct answer is option B

When the displacement in the harmonic motion is maximum then kinetic energy at the maximum point is minimum and the potential energy is maximum at that point.

So, when the displacement is maximum, spring force magnitude is also maximum because the force is proportional to the displacement and also the magnitude of the acceleration is maximum so, the net force is also maximum.

7 0

2 years ago

A motorcyclist drove 7 km at 57km/h and then another 7 km at 81 km/h. What was the average speed?

alex41 [277]

Answer:

The average speed of the car is 66.9 km/h

Explanation:

Here distance covered with the speed 57 km/h=7 km 

distance covered with the speed of 81 km/h=7 km

Average speed is equal to the ratio of total distance to the total time.

total distance= 7 + 7= 14 km

$time= \frac{distance}{speed}$

time taken to cover the first 7 km= 7/57 h

time taken to cover the second part of the journey = 7/81 h

average speed = $14/(7/57+7/81)=(14 \times 57 \times 81)/945=66.9 km/h$ 

Shortcut: 

When equal distances are covered with different speeds average speed=2 ab/(a+b) where a and b are the variable speeds in the phases. 

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2 years ago

Which example represents the impact of religion on culture in the United States? A. children receiving counseling at school B. f

dmitriy555 [2]

Answer:

D. Banks and offices closing on sunday.

Explanation:

Church is usually on sunday and people need a day off to do it because service is about 3 hours long. When banks and offices close on this day it shows how religion has affected our lives and our culture.

5 0

2 years ago

2 Ten identical lengths of wire are laid closely side-by-

Mice21 [21]

Answer:

(a) 0.71 mm

(b) 0.158 cubic cm

Explanation:

The width of one wire is the diameter of the wire.

(a) Let the diameter of each wire is d.

So, 10 d = 14.2 mm

d = 1.42 mm

radius of each wire, r = d/2 = 1.42/2 = 0.71 mm

(b) Length, L = 10 cm

The volume of the single wire is given by

$V =\pi\times r^2\times h \\\\V =3.14\times 0.071^2\times 10\\\\V =0.158 cm^3$

7 0

1 year ago

What are the components of friction?

Tresset [83]

<h2>Answer:</h2>

Friction:

When an object slips on a surface, an opposing force acts between the tangent planes which acts in the opposite direction of motion. This opposing force is called Friction. Or in other words, Friction is the opposing force that opposes the motion between two surfaces.

The main component of friction are:

Normal Reaction (R):

Suppose a block is placed on a table in the above picture, which is in resting state, then two forces are acting on it at that time.

The first is due to its weight mg which is working from its center of gravity towards the vertical bottom.

The second one is superimposed vertically upwards by the table on the block, called the reaction force (P). This force passes through the center of gravity of the block.

Due to P = mg, the box is in equilibrium position on the table.

Coefficient of friction ( μ ):

The ratio of the force of friction and the reaction force is called the coefficient of friction.

Coefficient of friction, µ = force of friction / reaction force

μ = F / R

The coefficient of friction is volume less and dimensionless.

Its value is between 0 to 1.

Advantage and disadvantage from friction force:

The advantage of the force of friction is that due to friction, we can walk on the earth without slipping.
Brakes in all vehicles are due to the force of friction.
We can write on the board only because of the force of friction.
The disadvantage of this force is that due to friction, some parts of energy are lost in the machines and there is wear and tear on the machines.

How to reduce friction:

Using lubricants (oil or grease) in machines.
Friction can be reduced by using ball bearings etc.
Using a soap solution and powder.

4 0

2 years ago