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3 years ago

Name two factors on which the heat energy librated by a body on cooling depends..

Physics

1 answer:

Lesechka [4]3 years ago

5 0

Explanation:

Heat liberated by a body depends on the mass of the body, the specific heat capacity of that body and the change in temperature experienced by the body.

Heat energy by a body depends on the surface area of the body A as well as the temperature of body T.

According to Stefan's law, rate of heat energy radiated by a body is given by P=σAeT^4

Thus more is the temperature of body, more is the heat radiated. Also mores is the surface area of body, more is the heat radiated.

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The food calorie, equal to 4186 J, is a measure of how much energy is released when food is metabolized by the body. A certain b

rewona [7]

Answer:

The hiker has to climb 941.26 to ''work off'' the calories.

Explanation:

Let's first find out how much energy the hiker gets from 150 food calories.

This is:

Energy = 150 * 4186

Energy = 627.9 kJ

To burn all of this off, we set it equal to the gravitational potential energy, and then solve for the height.

This is:

Gravitational Potential Energy (G.P.E) = 629700

G.P.E = mass * gravity * height

Thus,

mass * gravity * height = 629700

68 * 9.81 * height = 629700

height = 941.26 meters

5 0

3 years ago

Estimate how fast your hair grows, in units of m/s, assuming it takes 30 days for your hair to grow 1 inch. note that 1 inch =2.

VashaNatasha [74]

Answer:

1. 9.8 x 10^-7 cm/s

2. 50970 L

Explanation:

time, t = 30 days = 30 x 24 x 60 x 60 seconds = 2592000 seconds

length of hair, d = 1 inch = 2.54 cm

rate of growth = length of hair grows per second = 2.54 / 2592000

= 9.8 x 10^-7 cm/s

Thus, the grown rate of hair is 9.8 x 10^-7 cm/s.

2. length of the pool, l = 15 feet

width of the pool, w = 15 feet

height of pool, h = 8 feet

Volume of the pool, V = length x width x height

V = 15 x 15 x 8 = 1800 ft^3

To convert ft^3 into m^3 , we use

1 ft = 0.3048 m

so, 1 ft^3 = (0.3048)^3 m^3 = 0.0283 m^3

So, 1800 ft^3 = 1800 x 0.0283 = 50.97 m^3

now, 1 m^3 = 1000 L

So, 50.97 m^3 = 50.97 x 1000 L = 50970 L

3 0

3 years ago

Consider a rifle, which has a mass of 2.44 kg and a bullet which has a mass of 150 grams and is loaded in the firing chamber.Whe

svetlana [45]

Answer:

a. 0 kgm/s

b. 0 kgm/s

c. 66 kgm/s

d. -66 kgm/s

e. 0 kgm/s

f. -27.05 m/s

g. 173.68 N

h. 12.58 m/s

i. 0.772 m

j. 14487 J

Explanation:

150 g = 0.15 kg

a. Before the bullet is fired, both rifle and the bullet has no motion. Therefore, their velocity are 0, and so are their momentum.

b. The combination is also 0 here since the bullet and the rifle have no velocity before firing.

c. After the bullet is fired, the momentum is:

0.15*440 = 66 kgm/s

d. As there's no external force, momentum should be conserved. That means the total momentum of both the bullet and the rifle is 0 after firing. That means the momentum of the rifle is equal and opposite of the bullet, which is -66kgm/s

e. 0 according to law of momentum conservation.

f. Velocity of the rifle is its momentum divided by mass

v = -66 / 2.44 = -27.05 m/s

g. The average force would be the momentum divided by the time

f = -66 / 0.38 = 173.68 N

h. According the momentum conservation the bullet-block system would have the same momentum as before, which is 66kgm/s. As the total mass of the bullet-block is 5.1 + 0.15 = 5.25. The velocity of the combination right after the impact is

66 / 5.25 = 12.58 m/s

i. The normal force and also friction force due to sliding is

$F_f = N\mu = Mg\mu = 5.25*9.81*0.83 = 42.75N$

According to law of energy conservation, the initial kinetic energy will soon be transformed to work done by this friction force along a distance d:

$W = K_e$

$dF_f = 0.5Mv_0^2$

$d = \frac{Mv_0^2}{2F_f} = \frac{5.25*12.58^2}{2*42.75} = 0.772 m$

j.Kinetic energy of the bullet before the impact:

$K_b = 0.5*m_bv_b^2 = 0.5*0.15*440^2 = 14520 J$

Kinetic energy of the block-bullet system after the impact:

$K_e = 0.5Mv_0^2 = 0.5 * 5.25*12.58^2 = 33 J$

So 14520 - 33 = 14487 J was lost during the lodging process.

3 0

3 years ago

7. A car travels at 25 m/s to the North. It has an acceleration of 2 m/s to the south

tamaranim1 [39]

Answer:

-0.5 m/s2 as it comes to rest.

Explanation:

7 0

3 years ago

What is the purpose of setting a deadline for your goal

Nutka1998 [239]

Well, when you want to accomplish a goal, you can't take forever to do it now can you? No. The purpose of setting a deadline for your goal is for motivation. You become motivated to do it, instead of putting it off for later. You want to get it done in a reasonable amount of time.

3 0

3 years ago

Read 2 more answers

Name two factors on which the heat energy librated by a body on cooling depends..​

Name two factors on which the heat energy librated by a body on cooling depends..