can I skip gravitation and tissue chapter for class 9 annual examination?? which lessons are most important and which aren't??

A metal rod A and a metal sphere B, on insulating stands, touch each other. They are originally neutral. A positively charged ro

ryzh [129]

Answer:

The sphere is positively charged

Explanation:

This is because when the positively charged rod is brought near the metal rod A, the electrons in metal rod A and sphere B are attracted towards it into metal rod A while the positive charges in the are repelled into sphere B. So, when the charged rod is withdrawn, and metal rod A and sphere B are separated, metal rod A is now negatively charged, but sphere B is positively charged.

So, sphere B is positively charged.

3 0

3 years ago

Let A^=6i^+4j^_2k^ and B= 2i^_2j^+3k^. find the sum and difference of A and B

andreyandreev [35.5K]

Explanation:

Let $\textbf{A} = 6\hat{\textbf{i}} + 4\hat{\textbf{j}} - 2\hat{\textbf{k}}$ and $\textbf{B} = 2\hat{\textbf{i}} - 2\hat{\textbf{j}} + 3\hat{\textbf{k}}$

The sum of the two vectors is

$\textbf{A + B} = (6 + 2)\hat{\textbf{i}} + (4 - 2)\hat{\textbf{j}} + (-2 + 3)\hat{\textbf{k}}$

$= 8\hat{\textbf{i}} + 2\hat{\textbf{j}} + \hat{\textbf{k}}$

The difference between the two vectors can be written as

$\textbf{A - B} = (6 - 2)\hat{\textbf{i}} + (4 - (-2))\hat{\textbf{j}} + (-2 - 3)\hat{\textbf{k}}$

$= 4\hat{\textbf{i}} + 6\hat{\textbf{j}} - 5\hat{\textbf{k}}$

8 0

3 years ago

What changes occurred when Zoroastrianism became a state religion during the Sasanian Empire?

statuscvo [17]

Zoroastrianism affected the way the Persians governed their subjects by allowing the territories under their rule to worship their own religion.

8 0

3 years ago

How much heat is needed to raise the temperature of 9g of water by 17oC?

andre [41]

Well the heat that is needed to raise the temperature of 10g of water by 17oC is 7

6 0

3 years ago

You are coasting on your 12-kg bicycle at 13 m/s and a 5.0-g bug splatters on your helmet. The bug was initially moving at 1.5 m

Brut [27]

Answer:

a) Pi,c = 1066 kgm/s

b) Pi,b = 0.0075 kgm/s

c) ΔV = - 0.0007 m/s

d) ΔV = - 0.0008 m/s

Explanation:

Given:-

- The mass of the bicycle, mc = 12 kg

- The mass of passenger, mp = 70 kg

- The mass of the bug, mb = 5.0 g

- The initial speed of the bicycle, vpi = 13 m/s

- The initial speed of the bug, vbi = 1.5 m/s

Find:-

a.What is the initial momentum of you plus your bicycle?

b.What is the initial momentum of the bug?

c.What is your change in velocity due to the collision the bug?

d.What would the change in velocity have been if the bug were traveling in the opposite direction?

Solution:-

- First we will set our one dimensional coordinate system, taking right to be positive in the direction of bicycle.

- The initial linear momentum (Pi,c) of the passenger and the bicycle would be:

Pi,c = vpi* ( mc + mp)

Pi,c = 13* ( 12+ 70 )

Pi,c = 1066 kgm/s

- The initial linear momentum (Pi,b) of the bug would be:

Pi,b = vbi*mb

Pi,b = 0.005*1.5

Pi,b = 0.0075 kgm/s

- We will consider the bicycle, the passenger and the bug as a system in isolation on which no external unbalanced forces are acting. This validates the use of linear conservation of momentum.

- The bicycle, passenger and bug all travel in the (+x) direction after the bug splatters on the helmet.

Pi = Pf

Pi,c + Pi,b = V*(mb + mc + mp)

Where, V : The velocity of the (bicycle, passenger and bug) after collision.

1066 + 0.0075 = V*( 0.005 + 12 + 70 )

V = 1066.0075 / 82.005

V = 12.9993 m/s

- The change in velocity is Δv = 13 - 12.9993 = - 0.00070 m/s

- If the bug travels in the opposite direction then the sign of the initial momentum of the bug changes from (+) to (-).

- We will apply the linear conservation of momentum similarly.

Pi = Pf

Pi,c + Pi,b = V*(mb + mc + mp)

1066 - 0.0075 = V*( 0.005 + 12 + 70 )

V = 1065.9925 / 82.005

V = 12.99911 m/s

- The change in velocity is Δv = 13 - 12.99911 = -0.00088 m/s

7 0

3 years ago

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