OGOJNR:
i'm sure that d lord has a plan and purpose for ur life...i pray it wuld be actualized in jesus name...DO you remember hannah in d bible whom God answered her prayer,i pray that GOD almighty wuld answer ur prayers in jesus name.AMEN@horpe...nice post

Thanks Sir, this was inspiring. I also wish you all of life's most colourful and God's most beautiful things.

enry54:
PHYSICS Que. Please Don't Ignore!!!

1. A missile weighing 400N on the earth's surface is shot into the atmosphere to an altitude of 6.40 x 10^6m, taking the earth as a sphere of radius 6.40 x 10^6m. What would be the weight of the missile at that altitude?

2. Assuming that the mean density of the earth is 5500kg/m^3, that the constant of gravitation is 6.7 x 10^-11 and that the radius of the earth is 6400km. Find a value for the acceleration due to gravity at the earth's surface.

3. What would happen to the earth's period of revolution if its mass was three times as great as it is?

As Mathefaro has noted, this is an A-level/Pre-degree question which is a no no for O-levels/PUTME.

Why you decided to bring this in I wouldn't know but, nevertheless

1. You use this crazy formula
→g(r) = (R/R + H)^2 (acceleration due to gravity of body at a height, not to be mistaken with the gravitational potential of a body at a height V= - GM/ R + H)

→g(r)= (6.4 x 10 ^6/ 6.4 x 10^6 + 6.4 x 10^6)^2

→g(r)= 0.25m/s^2

Normally on the earth, g=10ms^-2, so mass can be gotten from there,

then W=mg
→400N=m x 10
→m=400/10
→m= 40kg

therefore, the weight of the Missile at the new Altitude is
W= mg(r)
W= 40 x 0.25
→W= 10N

2. Am not totally sure about the mass,
→W=mg
→W= d x V x g
→mg= d x v x g

→g cancels out,
→m= d x v
→m= 5500kg/ m3 x m3

→m3 cancels out m3, you are left with

→m= 5500kg

Applying
→g = Gm/R^2

→g= 6.67 x 10^ -11 x 5500/ (6400 x 10^3)^2

→g= 8.95 x 10^-21 m/s^2

3. You get an answer to this later in the morning...

Guys una no dy sleep

DrHost:
Pls what the chances of someone applying with poly ibadan nd upper class in civil engineering

Great chances, with prayers... Lots of prayer

mathefaro:
For candidates preparing for post utme? Way off the scope IMO

Na Jamb Questions! Based on the syllabus

Treasuregr8 view as usual.



Cutebumzy where art thee?

enry54:
Na Jamb Questions! Based on the syllabus

If I hear! I can say it with all authority that jamb will never set such question and neither will any school for PUTME. Because like I said earlier, it's beyond the scope of UTME even if as you put it, it's in the syllabus. For the fact that the topic is part of the syllabus doesn't mean they have to go deep to this level. For instance, when you check the math syllabus, you have calculus in it but there is a limit to which they can go in calculus questions (scope). Nevertheless, I believe horpeyemmi66 has done a good job up there. That should be the correct answer if I'm not mistaken.

Good morning to y'all

mathefaro:
If I hear! I can say it with all authority that jamb will never set such question and neither will any school for PUTME. Because like I said earlier, it's beyond the scope of UTME even if as you put it, it's in the syllabus. For the fact that the topic is part of the syllabus doesn't mean they have to go deep to this level. For instance, when you check the math syllabus, you have calculus in it but there is a limit to which they can go in calculus questions (scope). Nevertheless, I believe horpeyemmi66 has done a good job up there. That should be the correct answer if I'm not mistaken.

Good morning to y'all

.
1• It is a logical question and requires a logical reasoning...
The first question is all about the inverse square law of universal gravitation, I believe you know that...

Let the mass of earth be M
The mass of missile be m
While the distance is d
Thus. F=(GMm)/d²

Mere looking at the situation, GMm is constant anywhere... Right ?
So let F x d² = constant

F₁ x d₁² = F₂ x d₂²

F₂ = F₁ (d₁)²/ (d₂)²

F₂ = 400 x (6.4 x 10⁶)²/(12.8 x 10⁶)²

F₂ = 400 x (0.5)² = 400 (0.25) = 100N

Hmmmm been awhile here o...tight schedule lately

u guyz are really trying here cuz am loving the biology and english here...avnt seen much of chemistry though ...keep up d good work...peepz are benefiting...gudmrng

mathefaro:
If I hear! I can say it with all authority that jamb will never set such question and neither will any school for PUTME. Because like I said earlier, it's beyond the scope of UTME even if as you put it, it's in the syllabus. For the fact that the topic is part of the syllabus doesn't mean they have to go deep to this level. For instance, when you check the math syllabus, you have calculus in it but there is a limit to which they can go in calculus questions (scope). Nevertheless, I believe horpeyemmi66 has done a good job up there. That should be the correct answer if I'm not mistaken.

Good morning to y'all

2• Let M be the Mass of Earth
Let r be radius of the earth
Let p be the density of earth

g=GM/r² = G(pV)/r²

V(volume)= 4/3 • πr³

Thus g= Gp • 4/3 • πr

g= (6.7x10^-11 x 5500 x 4 x π x 6400 x 10³)/ 3

Pls cross check with calc.

g= 9.87 m/s²

mathefaro:
If I hear! I can say it with all authority that jamb will never set such question and neither will any school for PUTME. Because like I said earlier, it's beyond the scope of UTME even if as you put it, it's in the syllabus. For the fact that the topic is part of the syllabus doesn't mean they have to go deep to this level. For instance, when you check the math syllabus, you have calculus in it but there is a limit to which they can go in calculus questions (scope). Nevertheless, I believe horpeyemmi66 has done a good job up there. That should be the correct answer if I'm not mistaken.

Good morning to y'all

3• This, I can say it is sorta advanced but, they are all in our textbooks...

For revolution, MV²/r = Mg

Mw²r=mg

g=(2π/T)²r
g=4π²r/T²
T²=4π²r/g
T= 2π√(r/g)

Hence the mass is not dependent on the period.

Note: All questions answered are from O'level related textbooks and not A'level

enry54:
.
1• It is a logical question and requires a logical reasoning...
The first question is all about the inverse square law of universal gravitation, I believe you know that...

Let the mass of earth be M
The mass of missile be m
While the distance is d
Thus. F=(GMm)/d²

Mere looking at the situation, GMm is constant anywhere... Right ?
So let F x d² = constant

F₁ x d₁² = F₂ x d₂²

F₂ = F₁ (d₁)²/ (d₂)²

F₂ = 400 x (6.4 x 10⁶)²/(12.8 x 10⁶)²

F₂ = 400 x (0.5)² = 400 (0.25) = 100N

This doesn't go down well with me sir viz:

"F2= 400 x (0.5)2= 400 x (0.25) = 100N"

F=mg, isn't it?, but look what you've done...
F2= W x g
F2= mg x g
F2= 40 x 10 x 0.25(emphasis mine)

You should have gotten the mass as 40 before comparing it with the new gravitation acting on the body at that height.

You took the weight of the body on the Earth and multiplied with the gravitation acting on the body at that height, which for the want of a better word is illogical.

Mass is constant anywhere, but gravitational force g, varies being less at the equator and more pronounced at poles.

Don't confuse people for the love of God!

Would soon vet the rest you've done...

Cc mathefaro

horpeyemmi66:

This doesn't go down well with me sir viz:

"F2= 400 x (0.5)2= 400 x (0.25) = 100N"

F=mg, isn't it?, but look what you've done...
F2= W x g
F2= mg x g
F2= 40 x 10 x 0.25(emphasis mine)

You should have gotten the mass as 40 before comparing it with the new gravitation acting on the body at that height.

You took the weight of the body on the Earth and multiplied with the gravitation acting on the body at that height, which for the want of a better word is illogical.

Mass is constant anywhere, but gravitational force g, varies being less at the equator and more pronounced at poles.

Don't confuse people for the love of God!

Would soon vet the rest you've done...

Cc mathefaro

The equation you used to find the acceleration due to gravity at a height h above the earth crust is wrong... Check you textbook, let say the acceleration due to gravity above height h is g' with R as the radius of the earth

g=GM/R²
Thus g' at height h from the earth crust is

g'= GM/(R + h)²

Divide by g

Thus, g'/g = R²/(R + h)²

Therefore g' (acceleration due to gravity at height h) = g • R²/(R + h)²

By the way... Check how I got 0.25 I dint find g first... Take a look at the way I solved it once more...

People dey vex for here

to me ooo...the answer is 10N.using g=GM/R square
g=0.25M/S2
W=Mg
mass is constant nw
w=40*0.25=10N.
this is an advanced level question oo

OGOJNR:
to me ooo...the answer is 10N.using g=GM/R square
g=0.25M/S2
W=Mg
mass is constant nw
w=40*0.25=10N

Guy! g=GM/R²
Thus g' at height h from the earth crust is

g'= GM/(R + h)²

Divide by g

Thus, g'/g = R²/(R + h)²

Therefore g' (acceleration due to gravity at height h) = g • R²/(R + h)²
These things are in our textbooks! You don't just consider them

hen nw,which means g is equal to 0.25 nd mass is 40kg nw

OGOJNR:
hen nw,which means g is equal to 0.25 nd mass is 40kg nw

g' (acceleration due to gravity at height h ) is not 0.25....

Put g= Which is 10m/s²
R= which is the radius of the earth 6.4x10⁶
h= which is the height above the earth surface 6.4x10⁶
In the equation...
g' (acceleration due to gravity at height h) = g • R²/(R + h)²
You will get 2.5 as your answer dude!

*PHYSICS | LATENT HEAT 001

1. Which of the following lowers the melting point of substances?

A. Density

B. Pressure

C. Energy density

D. Specific latent heat of fusion

2. Heat is supplied to a test tube containing 100g of ice at its melting point. The ice melts completely in 1min. What is the power rating of the source of heat(latent heat of fusion of ice=336J/g)

3. The statements below were made by some students describing what happened during the determination of the melting point of solids
1. The temperature of the solid was constant until melting started
2. The temperature of the solid rose until melting started
3. During melting, the temperature was rising
4. During melting, the temperature was constant
5. The temperature continued to rise after all the solid had melted
6. The temperature stopped rising after all the solid had melted.

Which of the following gives correct statements in the right order?
A. 2, 4 & 5

B. 2, 3 & 6

C. 1, 3 & 6

D. 1, 3 & 5

E. 1, 4 & 5

4. What is the difference in the amount of heat given out by 4kg of steam and 4kg of water when both are cooled from 100°C to 80°C?( Specific latent heat of steam is 2,260,000J/kg, Specific heat capacity of water is 4200J/kg/k)

5. 80% of the heat supplied to a 30g block of ice at 0°C. Calculate the total heat energy supplied. (Specific latent heat of Ice= 336J/g)

6. Which of the following best explains why a person suffers a more severe burn when his skin is exposed to steam than when boiling water is poured unto his skin?

A. Steam is at a higher temperature than boiling water

B. Steam possess greater heat energy per unit mass than boiling water

C. Steam spreads easily over a wider area of the skin than boiling water

D. Steam penetrates more deeply into the skin than boiling water

7. Calculate the time to heat 2kg of water from 50°C to 100°C in an electric kettle taking 5A from a 210V supply (S.H.C. of water =4200J/kg/k)

8. How many grams of water, 17°C must be added to a 42g of Ice at 0°C to melt the ice completely? (S.H.C of Water=4200J/kg/k, Specific latent heat of fusion of Ice = 3.4 x 10^5 J/kg/k).
------------------------------------------------
Humanities, where are you guys, this is not a game of monopoly, we need you guys to do your thing a symphony is what we want.

horpeyemmi66:
*PHYSICS | LATENT HEAT 001

1. Which of the following lowers the melting point of substances?

A. Density

B. Pressure

C. Energy density

D. Specific latent heat of fusion

2. Heat is supplied to a test tube containing 100g of ice at its melting point. The ice melts completely in 1min. What is the power rating of the source of heat(latent heat of fusion of ice=336J/g)

3. The statements below were made by some students describing what happened during the determination of the melting point of solids
1. The temperature of the solid was constant until melting started
2. The temperature of the solid rose until melting started
3. During melting, the temperature was rising
4. During melting, the temperature was constant
5. The temperature continued to rise after all the solid had melted
6. The temperature stopped rising after all the solid had melted.

Which of the following gives correct statements in the right order?
A. 2, 4 & 5

B. 2, 3 & 6

C. 1, 3 & 6

D. 1, 3 & 5

E. 1, 4 & 5

4. What is the difference in the amount of heat given out by 4kg of steam and 4kg of water when both are cooled from 100°C to 80°C?( Specific latent heat of steam is 2,260,000J/kg, Specific heat capacity of water is 4200J/kg/k)

5. 80% of the heat supplied to a 30g block of ice at 0°C. Calculate the total heat energy supplied. (Specific latent heat of Ice= 336J/g)

6. Which of the following best explains why a person suffers a more severe burn when his skin is exposed to steam than when boiling water is poured unto his skin?

A. Steam is at a higher temperature than boiling water

B. Steam possess greater heat energy per unit mass than boiling water

C. Steam spreads easily over a wider area of the skin than boiling water

D. Steam penetrates more deeply into the skin than boiling water

7. Calculate the time to heat 2kg of water from 50°C to 100°C in an electric kettle taking 5A from a 210V supply (S.H.C. of water =4200J/kg/k)

8. How many grams of water, 17°C must be added to a 42g of Ice at 0°C to melt the ice completely? (S.H.C of Water=4200J/kg/k, Specific latent heat of fusion of Ice = 3.4 x 10^5 J/kg/k).
------------------------------------------------
Humanities, where are you guys, this is not a game of monopoly, we need you guys to do your thing a symphony is what we want.

1• B
2• Heat Supplied = Heat Required For Melting Ice
H = mL = 100 x 336 = 33600J

Power Rating = Energy Used Up/ Time
Power Rating = 33600/60
= 560J/s or 560w
3• The correct option is A as temp. Rises before and after melting...
Temp. Remains constant during melting...

4• Cooling steam from 100^oC to 80^oC Comprises of
(i) 100^oC of steam (gas) - 100^oC of water i.e change of state
(ii) 100^oC of water - 80^oC of water i.e change of temperature hence, Heat given out = mL + mcθ
Cooling water from 100^oC to 80^oC, heat given out is mcθ

Difference = mL + mcθ - mcθ =mL
= 4 x 2260000
=9040000J
5• Quant. Of Heat = 30 x 336
= 10080J
Thus. 80% of Total Heat = 10080J
Total Heat = (10080 x 100)/80
= 12600
6• (B) Steam possesses greater heat energy per Unit Mass.

7• Quant. Of Heat = mc(θ₂ - θ₁)
= 2 x 4200 x (50)
= 420kJ
Thus. Quant of Heat = IVt
t= 420000/(5x210)
t= 400s

8•Mass of Water (kg) 0.042kg
Heat Required For Melting = Heat Lost By Water
0.042 x 3.4 x 10⁵ = m x 4200 x (17-0)
71400m = 14280
m=0.2kg or 200g

@horpeyemmi66.. I thought you were about to prove me wrong in my previous question.... I hope you now understand the way I did it? Pls note that I will neva test you guys with a question I don't understand! In case I have a question I might not understand, I will indicate it in such question.

horpeyemmi66:
*PHYSICS | LATENT HEAT 001

1. Which of the following lowers the melting point of substances?

A. Density

B. Pressure

C. Energy density

D. Specific latent heat of fusion

2. Heat is supplied to a test tube containing 100g of ice at its melting point. The ice melts completely in 1min. What is the power rating of the source of heat(latent heat of fusion of ice=336J/g)

3. The statements below were made by some students describing what happened during the determination of the melting point of solids
1. The temperature of the solid was constant until melting started
2. The temperature of the solid rose until melting started
3. During melting, the temperature was rising
4. During melting, the temperature was constant
5. The temperature continued to rise after all the solid had melted
6. The temperature stopped rising after all the solid had melted.

Which of the following gives correct statements in the right order?
A. 2, 4 & 5

B. 2, 3 & 6

C. 1, 3 & 6

D. 1, 3 & 5

E. 1, 4 & 5

4. What is the difference in the amount of heat given out by 4kg of steam and 4kg of water when both are cooled from 100°C to 80°C?( Specific latent heat of steam is 2,260,000J/kg, Specific heat capacity of water is 4200J/kg/k)

5. 80% of the heat supplied to a 30g block of ice at 0°C. Calculate the total heat energy supplied. (Specific latent heat of Ice= 336J/g)

6. Which of the following best explains why a person suffers a more severe burn when his skin is exposed to steam than when boiling water is poured unto his skin?

A. Steam is at a higher temperature than boiling water

B. Steam possess greater heat energy per unit mass than boiling water

C. Steam spreads easily over a wider area of the skin than boiling water

D. Steam penetrates more deeply into the skin than boiling water

7. Calculate the time to heat 2kg of water from 50°C to 100°C in an electric kettle taking 5A from a 210V supply (S.H.C. of water =4200J/kg/k)

8. How many grams of water, 17°C must be added to a 42g of Ice at 0°C to melt the ice completely? (S.H.C of Water=4200J/kg/k, Specific latent heat of fusion of Ice = 3.4 x 10^5 J/kg/k).
------------------------------------------------
Humanities, where are you guys, this is not a game of monopoly, we need you guys to do your thing a symphony is what we want.

1.b 2. P=560w 3.a 4. H=9.03*10^6 5. H=8,064J 6.b 7. t=400s 8. M=200g

enry54:

3• This, I can say it is sorta advanced but, they are all in our textbooks...

For revolution, MV²/r = Mg

Mw²r=mg

g=(2π/T)²r
g=4π²r/T²
T²=4π²r/g
T= 2π√(r/g)

Hence the mass is not dependent on the period.

Note: All questions answered are from O'level related textbooks and not A'level

They are actually in the O-levels textbooks. Nice one

Wait,,,,


Na only scientists full here?

No Maths! No Economics! No government!

Umartins1:
Wait,,,,



Na only scientists full here?


No Maths! No Economics! No government!

I can always do Economics, my problem is who will put up Government questions?

cassyrooy:
I can always do Economics, my problem is who will put up Government questions?

I can but only if there is someone to fire me too.

cassyrooy:
Treasuregr8 view as usual.



Cutebumzy where art thee?

hi dear, av been off nairaland for a while. How u doin?

Umartins1:

I can but only if there is someone to fire me too.

Lets do it then!

Cutebumzy:
hi dear, av been off nairaland for a while. How u doin?

Welcome back sweetie, how has it been? Hope no stress ni?

missing all, where is estijaz ?