Which solid is the best thermal insulator

One event occurs at the origin at t equal to zero, and a second events occurs at the point x=5m along the x-axis at time with ct

Anastasy [175]

Answer:

The separation will be spacelike.

The first event can't cause the second event, as there exist an frame of reference in which both happens at the same time, in different positions, so, if there were causally connected, it will imply an instant connection, this is faster than light.

Explanation:

We can define the separation between two events (using the + - - - signature) as :

$(\Delta s )^2 = (ct_2 - c t_1 )^2 - (x_2 - x_1)^2$

where the separation will be lightlike if is equal to zero, timelike if is positive and spacelike if is negative.

For our problem

$c t_1 = 0$

$x_1 = 0$

$ct_2 = 4 \ m$

$x_2 = 5 \ m$

$(\Delta s )^2 = (4 \ m - 0 )^2 - ( 5 \ m - 0)^2$

$(\Delta s )^2 = (4 \ m )^2 - ( 5 \ m 0)^2$

$(\Delta s )^2 = 16 \ m^ 2 - 25 \ m^2$

$(\Delta s )^2 = - 9\ m^2$

So the separation will be spacelike, and the first event can't cause the second event, as there exist an frame of reference in which both happens at the same time, in different positions, so, if there were causally connected, it will imply an instant connection, this is faster than light.

8 0

3 years ago

A measure of the average kinetic energy of the individual particles in an object is called

svlad2 [7]

<h2>Answer: Temperature </h2>

Temperature is a physical quantity that reflects the amount of heat in a body or medium. This amount of heat is related to the internal energy of a system (thermodynamically speaking), <u>according to the movement (speed) of each of the particles that compose it</u>, this means that it is related to its kinetic energy.

Therefore, the higher the kinetic energy, the higher the thermal energy in the system and the higher the temperature.

7 0

3 years ago

Four forces are exerted on a disk of radius R that is free to spin about its center, as shown above. The magnitudes are proporti

Dmitry_Shevchenko [17]

The given magnitude of forces of F₁ = F₄, F₂ = F₃, F₁ = 2·F₂, give the

forces that exert zero net torque on the disk as the options;

(B) F₂

(D) F₄

<h3>How can the net torque on the disk be calculated?</h3>

The given parameters are;

F₁ = F₄

F₂ = F₃

F₁ = 2·F₂

Therefore;

F₄ = 2·F₂

In vector form, we have;

$\vec{F_4} = \mathbf{\frac{\sqrt{3} }{2} \cdot F_4 \cdot \hat i - 0.5 \cdot F_4 \hat j}$

$\vec{F_2} = \mathbf{ -F_2 \, \hat j}$

Clockwise moment due to F₄, M₁ = $-0.5 \times F_4 \, \hat j \times \dfrac{R}{2}$

Therefore;

$M_1 =- 0.5 \times 2 \times F_2 \, \hat j \times \dfrac{R}{2} = \mathbf{ -F_2 \, \hat j \times \dfrac{R}{2}}$

Counterclockwise moment due to F₂ = $-F_2 \, \hat j \times \dfrac{R}{2}$

Given that the clockwise moment due to F₄ = The counterclockwise moment due to F₂, we have;

Two forces that combine to exert zero net torque on the disk are;

F₂, and F₄

Which are the options; (B) F₂, and (D) F₄

Learn more about the resolution of vectors here:

brainly.com/question/1858958

4 0

2 years ago

Two speedboats are traveling at the same speed relative to the water in opposite directions in a moving river. An observer on th

DENIUS [597]

Answer:

a) vboat = 5.95 m/s b) vriver= 1.05 m/s

Explanation:

a) As observed from the shore, the speed of the boats can be expressed as the vector sum, of the boat speed relative to the water and the river speed relative to the shore, as follows:

vb₁s = vb₁w + vrs

In one case, the boat is moving in the same direction as the water:

vb₁s = vb₁w + vrs = 7.0 m/s (1)

For the other boat, it is clear that is moving in an opposite direction:

vb₂s = vb₂w - vrs = 4.9 m/s (2)

As we know that vb₁w = vb₂w, adding both sides, we can remove the river speed from the equation, as follows:

vb₁w = vb₂w = $\frac{7.0 m/s + 4.9 m/s}{2} =5.95 m/s$

b) Replacing this value in (1) and solving for vriver, we have:

vriver = 7.0 m/s - 5.95 m/s = 1.05 m/s

(we could have arrived to the same result subtracting both sides in (1), and (2))

3 0

2 years ago

PLEASE HELP!

luda_lava [24]

Answer:

When a body is placed on a table top, it exerts a force equal to its weight downwards on the table top but does not move or fall. (i) Name the force exerted ...

5 0

2 years ago