||Homework Help||Kindergarten-University.

akhl

@akhl

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Posted: 14 years ago

#151

@Aditi
1. Nitrogen can have both 3 and 5 valencies. In NH3, there is a lone pair of electrons on N. This lone pair is utilized in forming coordinate covalent bond with H+ in NH4^+

Note: Coordinate colvalent bond is a type of covalent bond in which two atoms share a pair of electrons and both the shared electrons come from the same atom.

2. O has negative charge.

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Aditi_97

@Aditi_97

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Posted: 14 years ago

#152

Thank you so much @akhl 😃 👏

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226079

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Posted: 14 years ago

#153

Chemistry - What is a 'nitrogenous' fertiliser?

Ohh and 5 interesting facts about atoms?

Edited by siddhi209 - 14 years ago

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596277

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Posted: 14 years ago

#154

@ akhl, thanks so much for helping me with that radical problem, I understand it much better now =)

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akhl

@akhl

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Posted: 14 years ago

#155

@sidhi209,
Nitrogenous fertilizers are fertilizers that contain nitrogen.
Examples:
Ammonium sulfatte (NH₄)₂SO₄
Ammonium nitrate NH₄NO₃
Ammonia NH₃5 interesting facts about atoms:
1. An atom consiss of a nucleus at the center surrounded by a cloud of negatively charged electrons.

2.Hydrogen-1 has 1 proteon and no neutron in its nucleus. All other atoms have protons and neutrons inside their nucleus.

3. The name "atom" comes from the Geek word "atomos", which means something which cannot be divided further.

4. Atoms are so tiny that they can be observed only with microscopes.

5. Atoms combine to form molecule.

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226079

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Posted: 14 years ago

#156

@ akhl : Thank you soo much, it has helped me a lot, thanks :)

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596277

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Posted: 14 years ago

#157

PHYSICS

A car is travelling on a highway

Can it have a negative velocity & a positive acceleration at the same time?

Can the car change d direction of its velocity when travelling with constant acceleration?

I'm guessing yes for the first one.

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596277

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Posted: 14 years ago

#158

Physics:

A person wearing a shoulder harness can survive a car crash if the acceleration is smaller than -300m/s^2. Assuming constant acceleration, how far must the front end of the car collapse if it crashes while going 101km/h?

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akhl

@akhl

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Posted: 14 years ago

#159

@Ayeshaa,

A car is travelling on a highway

Can it have a negative velocity & a positive acceleration at the same time?
Yes, it is possible if the car is moving towards the direction which is taken as negative and its speed is reducing. For example, assume that we take North as positive. The car is moving towards South. Then its velocity is negative. If the car's speed is decreasing with time, it means it acceleration is towards North, which means it has positive acceleration.

Can the car change d direction of its velocity when travelling with constant acceleration?

Are you sure the question says constant acceleration and not zero acceleration?
If it says zero acceleration, then answer is No.
If it says constant acceleration, then answer is yes. Example: Throw an object upward. Ignoring air resistance, it has constant acceleration of g (acceleration due to gravity) downward. Initially it moves upward. On reaching the top of its path, it changes direction and starts moving doward.

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akhl

@akhl

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Posted: 14 years ago

#160

@Ayeshaa,

A person wearing a shoulder harness can survive a car crash if the acceleration is smaller than -300m/s^2. Assuming constant acceleration, how far must the front end of the car collapse if it crashes while going 101km/h?

a = -300 m/s^2
u = 101 km/h = 101 * 1000/(3600) = 28.06 m/s
v = 0
S = ?
v^2 = u^2 + 2*a*S
0 = 28.06^2 + 2*(-300)*S
0 = 787.114 - 600 S
787.114 = 600 S
S = 787.114/600
S = 1.3 m (Answer)

Note: I used u for initial velocity, v for final velocity, S for displacement. Use some other symbols if you want. To convert 101 km/h into m/s, remember that 1 km = 1000 m and 1h = 3600 s

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