A _______ is a repeating disturbance or vibration that transfers or moves energy from place to place without transporting mass.

High-altitude mountain climbers do not eat snow, but always melt it first with a stove. To see why, calculate the energy absorbe

Vikki [24]

Answer:

a) $Q=467443.8\ J$

b) $Q_m=299700\ J$

c) $Q_2=131859\ J$

Explanation:

Given:

specific heat of ice, $c_i=2100\ J.kg^{-1}.^{\circ}C^{-1}$

latent heat of fusion of ice, $L=333000\ J.kg^{-1}$

specific heat of water, $c_w=4186\ J.kg^{-1}.^{\circ}C^{-1}$

(a)

mass of snow, $m_s=0.9\ kg$

initial temperature of snow, $T_{is}=-15^{\circ}C$

Final temperature of the consumed mass, $T_f=37^{\circ}C$

Now the energy absorbed from the body after eating this snow:

$Q=m_s.c_i.\Delta T_i+m_s.L+m_s.c_w.\Delta T_w$

$Q=0.9\times 2100\times (0-(-15))+0.9\times 333000+0.9\times 4186\times (37-0)$

$Q=467443.8\ J$

(b)

Energy absorbed from the body in melting the ice is the total latent heat:

$Q_m=m_s.L$

$Q_m=0.9\times 333000$

$Q_m=299700\ J$

(c)

initial temperature of water, $T_{iw}=2^{\circ}C$

final temperature of water, $T_{iw}=37^{\circ}C$

Now, the amount of energy invested by body for the water at this condition:

$Q_2=m_s.c_w.\Delta T_2$

$Q_2=0.9\times 4186\times (37-2)$

$Q_2=131859\ J$

3 0

3 years ago

Suppose one of the Global Positioning System satellites has a speed of 4.46 km/s at perigee and a speed of 3.54 km/s at apogee.

lys-0071 [83]

To solve this problem it is necessary to apply the concepts related to Kepler's second law and the conservation of angular momentum.

Kepler's second law tells us that the vector radius that unites a planet and the sun sweeps equal areas at equal times, that is, when the planet is farther from the sun, the speed at which it travels is less than when it is close to the sun.

The angular momentum is defined as

$L = m*r*v$

Where,

m= mass

r = Radius

v = Velocity

For conservation of angular momentum

$L_{apogee}=L_{perigee}$

$mv_a*r_a = mv_p*r_p$

$v_a*r_a= v_p*r_p$

$r_a = \frac{v_p*r_p}{v_a}$

$r_a = \frac{(4.46)(2.23*10^4)}{(3.54)}$

$r_a = 2.81*10^4km$

Therefore the corresponding distance at apogee is $2.81*10^4km$

3 0

3 years ago

A beam of unpolarized light in air strikes a flat piece of glass at an angle of incidence of 54.2 degrees. If the reflected beam

Stels [109]

Answer:

correct option is B. 1.39

Explanation:

given data

angle of incidence (θ) = 54.2 degrees

to find out

index of refraction of the glass

solution

we know that here reflected beam is completely polarized

so angle of incidence = angle of polarized ....................1

for reflective index we apply here Brewster law that is

μ = tan(θ) ...............2

put here θ value we get

μ = tan(54.2)

μ = 1.386

so correct option is B. 1.39

6 0

3 years ago

Read 2 more answers

Why are voltages always measured between two points??

sukhopar [10]

Answer:

We describe electrical circuits similarly: current is the rate at which charge flows past a point, while the voltage is effectively like an electrical “pressure.” Voltage is always measured between two points and indicates the force “pushing” charges to flow from one point to another.

7 0

3 years ago

An object is at rest on the ground. The object experiences a downward gravitational force from Earth. Which of the following pre

Montano1993 [528]

Answer:

A) and B) are correct.

Explanation:

If the object is at rest, it means that no net force is exerted on it.

As the object experiences a downward gravitational force from Earth, in order to be at rest, it must experience an upward force with the same magnitude as the gravitational force on the object.

This force is supplied by the normal force, which can adopt any value in order to meet the condition imposed by Newton´s 2nd Law, and is always perpendicular to the surface on which the object is placed (in this case, the ground).

At a molecular level, this normal force is supplied by the bonded molecules of the ground that behave like small springs being compressed by the molecules of the object, exerting an upward restoring force upward on them.

So, the statements A) and B) are true.

6 0

3 years ago

Read 2 more answers