# Physics: Post your doubts here!

#### Physicist

How to sketch this velocity-time graph?
see question 1 at

#### [email protected]

Can anyone explain this?

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#### KashishV

Can anyone explain this?

I know it's quite late, but I hope the explanation helps nonetheless.
The spring is moving vertically up and down, with equilibrium point being in the centre. At "lowest point of its motion" the mass has MAXIMUM displacement downwards. And at maximum displacement, we know that potential energy is maximum and kinetic energy is minimum(=0) therefore velocity=0 at lowest point and answer is D

Any one can help in physics practical paper 32 may/ June 19
i dont get the value of x in question 1

#### A*(a*)

Is there any whatsapp group for this group and if yes can someone kindly add me over there

#### A*(a*)

Should I tell my number ?

#### [email protected]

How to solve part b?

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#### KashishV

How to solve part b?

Hi, firstly this is a physics forum and your question is chemistry-related. Please be mindful henceforth
As to your question, it's quite a memory based answer. You need to know that MgCl2 dissolves in water to give Mg(OH)2+HCl; Since one product is basic and the other is acidic, your best guess is pH 7.
in case of MgO, you need to know that it hardly dissolves/is slightly soluble. It is more of a surface reaction that occurs in which Mg(OH)2 is produced. As a result, you predict a high pH. Dont go till 14, Mg(OH)2 is not as strong of an alkali.

#### asra_070

pls help with this

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#### [email protected]

Hi, firstly this is a physics forum and your question is chemistry-related. Please be mindful henceforth
As to your question, it's quite a memory based answer. You need to know that MgCl2 dissolves in water to give Mg(OH)2+HCl; Since one product is basic and the other is acidic, your best guess is pH 7.
in case of MgO, you need to know that it hardly dissolves/is slightly soluble. It is more of a surface reaction that occurs in which Mg(OH)2 is produced. As a result, you predict a high pH. Dont go till 14, Mg(OH)2 is not as strong of an alkali.
Sorry. I didn't notice at that time and thanks.

#### dasbutt

how will the diagram be drawn for this?

#### Marvis

Can anyone help me with this?? "B"

#### Marvis

To do that we need to use formula F=MA
Horizontal component will be ( 2m/s^2 * 0.05kg = 1N to the left
Vertical component are caused by the effect of gravitational pull, if Mechanics "10m/s^2" Physics "9,81m/s^2". Simply use 0.05kg * 10m/s^2 = 0.5N downwards.

Solving using Pythagoras theorem, tan-1( 1 / 0.5 ) 63.4 degrees

#### Thought blocker

View attachment 65229
Explanation for X:
Resultant force = 20 N to left
Torque = 20 * 0.5 = 10 Nm (clockwise)

Explanation for Y:
Resultant force = 20 N to left
Torque = 20 * 0.5 = 10 Nm (anti-clockwise)

A is correct

#### Thought blocker

Can anyone help me with this?? "B"View attachment 65228
Consider the weight of a column of air of cross-sectional area A and height h stretching from sea level to the edge of the atmosphere.
The density of the air decreases linearly with height above sea level, so the average density of air in the column is ρ/2 where ρ is the density of air at sea level.
The difference in pressure between the bottom and the top of the column of air is P, the atmospheric pressure at sea level.
The weight of the air column is ρgAh/2 and therefore P = ρgh/2

Solve for h

#### Physicist

Can anyone help me with this?? "B"View attachment 65228