Which of the following instrument measure time most accurately

True or false:slow movements of mantle rock called radiation transfer heat in the mantle.

RUDIKE [14]

The best answer between the two options would be the second choice B) FALSE.

8 0

4 years ago

A rock is thrown upward from the top of a 30 m building with a velocity of 5 m/s. Determine its velocity (a) When it falls back

Kobotan [32]

Answer:

a) 5 m/s

b) 17.8542 m/s

c) 24.7212 m/s

0.229

Explanation:

t = Time taken

u = Initial velocity = 5 m/s

v = Final velocity

s = Displacement

a = Acceleration due to gravity = 9.81 m/s²

$v=u+at\\\Rightarrow 0=5-9.81\times t\\\Rightarrow \frac{-5}{-9.81}=t\\\Rightarrow t=0.51 \s$

$s=ut+\frac{1}{2}at^2\\\Rightarrow s=5\times 0.51+\frac{1}{2}\times -9.81\times 0.51^2\\\Rightarrow s=1.27\ m$

So, the stone would travel 1.27 m up

$v^2-u^2=2as\\\Rightarrow v=\sqrt{2as+u^2}\\\Rightarrow v=\sqrt{2\times 9.81\times 1.27+0^2}\\\Rightarrow v=5\ m/s$

Velocity as the rock passes through the original point is 5 m/s

$s=ut+\frac{1}{2}at^2\\\Rightarrow 1.27=0t+\frac{1}{2}\times 9.81\times t^2\\\Rightarrow t=\sqrt{\frac{1.27\times 2}{9.81}}\\\Rightarrow t=0.51\ s$

Time taken to reach the original point is 0.51+0.51 = 1.02 seconds

So, total height of the rock would fall is 30+1.27 = 31.27 m

$s=ut+\frac{1}{2}at^2\\\Rightarrow 16.27=0t+\frac{1}{2}\times 9.81\times t^2\\\Rightarrow t=\sqrt{\frac{16.27\times 2}{9.81}}\\\Rightarrow t=1.82\ s$

Time taken by the stone to reach 15 m above the ground is 1.82+0.51 = 2.33 seconds

$v=u+at\\\Rightarrow v=0+9.81\times 1.82\\\Rightarrow v=17.8542\ m/s$

Speed of the ball at 15 m above the ground is 17.8542 m/s

$s=ut+\frac{1}{2}at^2\\\Rightarrow 31.27=0t+\frac{1}{2}\times 9.81\times t^2\\\Rightarrow t=\sqrt{\frac{31.27\times 2}{9.81}}\\\Rightarrow t=2.52\ s$

$v=u+at\\\Rightarrow v=0+9.81\times 2.52\\\Rightarrow v=24.7212\ m/s$

Speed of the stone just before it hits the street is 24.7212 m/s

F = Force

m = Mass = 100 kg

g = Acceleration due to gravity = 9.81 m/s²

s = Displacement = 4 km = 4000 m

P = Power = 1 hp = 745.7 Watt

t = Time taken = 20 minutes = 1200 seconds

μ = Coefficient of sliding friction

F = μ×m×g

⇒F = μ×100×9.81

W = Work done = F×s

P = Work done / Time

⇒P = F×s / t

$745.7=\frac{\mu \times 981\times 4000}{1200}\\\Rightarrow \mu=\frac{747.5\times 1200}{981\times 4000}\\\Rightarrow \mu=0.229$

Coefficient of sliding friction is 0.229

8 0

3 years ago

A child on a playground swings through a total of 32°. If the displacement is equal on each side of the equilibrium position, wh

sashaice [31]

Let L = length of the swing.

Let the lowest position of the swing be the reference point.
Therefore in the lowest position,
The height of the swing = 0,
The support for the swing is at height = L.

At 32° swing relative to the vertical,
The height of the swing is
A = L - Lcos(32°) = L[1 - cos(32°)] = 0.152L

Answer:
The amplitude is 0.152*L, where L = length of the swing.

6 0

4 years ago

1. how to find out the elecronic structure of<br> i. lithium<br> ii. potassium<br> iii. sodium

Setler [38]

Answer:

See explanation

Explanation:

To find out the electronic structure of each element, you must know the number of electrons it contains.

If you find that out(the number of electrons in the neutral atom of an element is the same as its atomic number). Then you arrange those electrons in such a way that the first shell has only two electrons and subsequent shells have eight electrons.

Look up the groups to which the elements belong in the periodic table All the elements are in group 1 so the last shell must have only one electron.

7 0

3 years ago

A conducting loop is lying flat on the ground. The north pole of a bar magnet is grought down toward the loop. As the magnet app

IceJOKER [234]

Answer:

The current in the loop will flow in anticlockwise direction , and the magnetic field created by the induced current point up.

Explanation:

7 0

3 years ago