Which way does heat travel? Explain your answer.

Maru [420]

Because gas particles in the air like particles of all fluids are constantly moving and bumping into things, they exert pressure. The pressure exerted by the air in the atmosphere is greater close to Earth's surface and decreases as you go higher above the surface.

Explanation:

Fill roughly one-third of a cup with water. Then, cover the mouth of the cup completely with a flat, hard cardboard. Using your hand to keep it in place, turn the cup upside down. When you remove your hand, the the cardboard stays in place.

One would expect that due to gravity, the water will fall, and even the cardboard will. However, it does not, which means that something must be applying an upward force on the cardboard. This is nothing other than air pressure, which applies a force across the surface of the cardboard in an upward direction.

Thus we can demonstrate that air exerts pressure, because otherwise, the water would have fallen.

3 0

3 years ago

What is the acceleration of a proton moving with a speed of 7.0 m/s at right angles to a magnetic field of 1.7 t ?

Ivenika [448]

We know that a charge moving in a magnetic field is subject to the force:
F = q · v · B

But we also know that:
F = m · a

Therefore, it must be:
m · a = q · v · B

And solving for a:
a = q · v · B / m

Recall that for a proton:
q = 1.6×10⁻¹⁹ C
m = 1.673×10⁻²⁷ kg

Now, you can find:
a = 1.6×10⁻¹⁹ · 7.0 · 1.7 / 1.673×10⁻²⁷
= 1.14×10⁹ m/s²

Hence, the acceleration of the proton is 1.14×10⁹ m/s².

8 0

3 years ago

Space debris left from old satellites and their launchers is becoming a hazard to other satellites. (a) Calculate the speed of a

Pie

Answer:

Part a)

$v = 7407.1 m/s$

Part b)

$v_{rel} = 1.05 \times 10^4 m/s$

Explanation:

Part a)

As we know that orbital velocity at certain height from the surface of Earth is given as

$v = \sqrt{\frac{GM}{R+h}}$

here we know that

$M = 5.98 \times 10^{24} kg$

$R = 6.37 \times 10^6 m$

$h = 900 km = 9.0 \times 10^5 m$

now we have

$v = \sqrt{\frac{(6.67 \times 10^{-11})(5.98 \times 10^{24})}{6.37 \times 10^6 + 9.0 \times 10^5}}$

$v = 7407.1 m/s$

Part b)

When a loose rivet is moving in same orbit but at 90 degree with the previous orbit path then in that case the relative speed of the rivet with respect to the satellite is given as

$v_{rel} = \sqrt{2} v$

$v_{rel} = 1.05 \times 10^4 m/s$

6 0

3 years ago

An example of when total internal reflection occurs is when all the light passing from a region of higher index of refraction to

Amiraneli [1.4K]

Answer:

is reflected back into the region of higher index

Explanation:

Total internal reflection is a phenomenon that occurs when all the light passing from a region of higher index of refraction to a region of lower index is reflected back into the region of higher index.

According to Snell's law, refraction of ligth is described by the equation

$n_1 sin \theta_1 = n_2 sin \theta_2$

where

n1 is the refractive index of the first medium

n2 is the refractive index of the second medium

$\theta_1$ is the angle of incidence (in the first medium)

$\theta_2$ is the angle of refraction (in the second medium)

Let's now consider a situation in which

$n_1 > n_2$

so light is moving from a medium with higher index to a medium with lower index. We can re-write the equation as

$sin \theta_2 = \frac{n_1}{n_2}sin \theta_1$

Where $\frac{n_1}{n_2}$ is a number greater than 1. This means that above a certain value of the angle of incidence $\theta_1$ , the term on the right can become greater than 1. So this would mean

$sin \theta_2 > 1$

But this is not possible (the sine cannot be larger than 1), so no refraction occurs in this case, and all the light is reflected back into the initial medium (total internal reflection). The value of the angle of incidence above which this phenomen occurs is called critical angle, and it is given by

$\theta_c =sin^{-1}(\frac{n_2}{n_1})$

8 0

4 years ago

A uniform steel girder of weight 22KN and of length 12m is lifted off the ground at one end by means of a crane. When the raised

Keith_Richards [23]

Answer:

Explanation:

For free body diagram see attached sheet .

W is weight of steel girder acting at the middle point of its length . T is tension in the cable .

OB = √ ( 12² - 2² )

= 11.83 m .

OC = 11.83 / 2 = 5.915 m

Taking moment of tension T and weight W about point O

W x OC = T x OB

22 x 5.915 = T x 11.83

T = 22 x 5.915 / 11.83

= 11 kN

Considering forces acting in vertical direction and equating forces in opposite direction

T + R = W

R = W - T

= 22 - 11 = 11 KN

So force of grinder on the ground = R

= 11 KN.

8 0

3 years ago