Segipaul:
1. How much work is needed to stop a 20g bullet moving with a speed of 150m/s

The work needed to stop the bullet = energy possessed by the moving bullet(kinetic energy)
M = 20/1000 = 1/50kg (converted the g to kg)
V = 150m/s
K.E = ½mv²
=> ½*1/50*150*150
= 225J

2. An object of mass 10kg is placed on an inclined plane at 30degree to the horizontal. Calculate the reaction between the two surfaces (g=10m/s^2)

m = 10kg; g = 10m/s², © = 30^o(let theta = ©);
Reaction force, R = mgCos©;
=> R = 10*10*Cos30
=> R = 100*0.866
=> R =86.6N

Battery low o!! I'll continue later

#a lens of focal length 12cm form an upright image three times d size of a real object. D distance between d object and d image is. #a load of 5N gives an extention of O.56cm in d wire which obeys hooke law. What is d extention cause by a load of 20N

Segipaul:

3. A 5kg mass on a horizontal platform accelerated at the rate of 0.1m/s^2 when a horizontal force of 10N is applied to it. Calculate the coefficient of friction between it and the platform (g=10m/s^2)

m = 5kg; a = 0.1m/s²; horizontal force = 10N
Frictional force, F = ?
Accelerating force f = ma
= 5*0.1 = 0.5N
Frictional force = Horizontal force - accelerating force
F = 10 - 0.5 = 9.5N
Reaction force, R = mg
=> 5*10 = 50N

Therefore, the coefficient of friction, U = F/R
=> 9.5/50
= 0.19
It has no unit

Benjaminbest:
#a lens of focal length 12cm form an upright image three times d size of a real object. D distance between d object and d image is.

f=12cm; v = 3u
Using the mirror formula, 1/f = 1/u + 1/v;
1/12 = 1/3u + 1/u
multiplying through by 12u (l.c.m.), we have
12u(1/12) = 12u(1/3u) + 12u(1/u)
u = 4 + 12
u = 16
Therefore v = 3*16 = 48
Therefore, the distance between the object and image = u + v = 16 + 48 = 64cm
(I forgot it's a real image so it's i nthe front of the mirror, which is the same side on which the object is)
v + u = 48 - 16= 32cm

#a load of 5N gives an extention of O.56cm in d wire which obeys hooke law. What is d extention cause by a load of 20N

According to Hooke's law, f = ke
F1 = 5N, e1 = 0.56cm, f2 = 20N, e2 = ?
F1/e1 = f2/e2
5/0.56 = 20/ e2
e2 = 4*0.56 = 2.24cm

try again

physics.......as a physicist if u are not good with unit it is easy for u to b thrown off balance in physics we have two physical quantity which are fundamental and derived unit. Fundamental unit are unit which can not broken down because dey occur in a single form e.g
fundamental unit unit name/abbrev
Length metre m
time second s
temperature kelvin k
luminous intensity candela cd
mass kilogramme kg
cureent ampere A

we also have derive a combination of fundamental unit e.g
derived unit unit name abbrev
velocity metre persec ms-1
force newton N
density kilograme cubicmetre kgm-3
potential difference volt v
acceleration mete persec square
charge coloumb Q
resistance ohm
inductance henry H
capacitance farad f
magnetic field tesla T
magnetic flux weber w

i no dis is very short but am kind of busy ryt na update resume later

#a load of 5N gives an extention of O.56cm in d wire which obeys hooke law.
What is d extention cause by a load of 20N[/quote]

lemme try...
hooke's law states, F=ke.
when F=5N, e=0.56, k=?
F=ke, k=F/e
5/0.56=k
k=8.92......

so when F=20. k=8.92, e=?
F/k=e
20/8.92=2.24cm...

pls correct me if am wrong....

i first question is wrong not d second one so answer d first

Benjaminbest:
try again

what does this mean, that I'm wrong? I'm anxiously waiting for your correction......Albeit the post have has been modified.

mathefaro:
what does this mean, that I'm wrong? I'm anxiously waiting for your correction......Albeit the post have been modified.

no doubt d second question u got it ryt but d first is wrong

Benjaminbest:
no doubt d second question u got it ryt but d first is wrong

@Benjamin
let's know where he got it wrong....
we are here to learn

@Mathefaro...n other maths expert in d house...
Help me solve this:

1. The first term of an AP is 3 and the eleventh term is 18. Find the number of terms in the progression if the sum is 81.



thank u

Destilo:
@Mathefaro...n other maths expert in d house...
Help me solve this:

1. The first term of an AP is 3 and the eleventh term is 18. Find the number of terms in the progression if the sum is 81.



thank u

a = 3, T₁₁ = 18; Sn = 81, n = ?
For an arithmetic progression, A.P, Tn = a + (n - 1)d
Hence,T₁₁ = a + 10d = 18
And since a = 3, 3 + 10d = 18
10d = 15
d = 3/2 = 1.5
Also, for an A.P, Sn = (n[2a + (n - 1)d])/2,
Hence Sn = (n[2a + (n - 1)d])/2 = 81
Recall that a = 3 and d = 1.5
Therefore Sn = (n[2*3 + (n - 1)1.5])/2 =81
Cross multiplying gives:
n(6 + 1.5n - 1.5) = 162
=> n(1.5n + 4.5) = 162
=> 1.5n² + 4.5n - 162 = 0
=> use any suitable method to solve the quadratic equation to get n as 9, the other value is negative(-12) and will be discarded since n cannot be negative

Benjaminbest:
no doubt d second question u got it ryt but d first is wrong

Since you think it's wrong, I'm very eager to see the right solution boss.

i got d question from jamb past questions after solving it i notice dat my answer is not even among d options provided same so i tink dey are wrong because dey said d answer is 32.....
First d image is real dat makes it positive
second we are not solving for d object distance alone
1_ =1_ + 1_
12 3u u
d l.c.m is 3u

1_=1___+3 =48_ =16
12 3u 3
mag=v_
u
3*16=48 is d distance between both of dem
48-16=32

lemme no if u are not clear

mathefaro:

f=12cm; v = 3u
Using the mirror formula, 1/f = 1/u + 1/v;
1/12 = 1/3u + 1/u
multiplying through by 12u (l.c.m.), we have
12u(1/12) = 12u(1/3u) + 12u(1/u)
u = 4 + 12
u = 16
Therefore v = 3*16 = 48
Therefore, the distance between the object and image = u + v = 16 + 48 = 64cm
(I forgot it's a real image so it's i nthe front of the mirror, which is the same side on which the object is)
v + u = 48 - 16= 32cm
According to Hooke's law, f = ke
F1 = 5N, e1 = 0.56cm, f2 = 20N, e2 = ?
F1/e1 = f2/e2
5/0.56 = 20/ e2
e2 = 4*0.56 = 2.24cm

guy u are good dat is d truth but u have to see boyond d question dat is given before solving it

lets deliberate on d topic density after den we will answer few question.....so guys what idea do u have on dis topic

Benjaminbest:
guy u are good dat is d truth but u have to see boyond d question dat is given before solving it

You still haven't told me where I got it wrong o, you got 32cm like I did after modifying your post, does that mean also wrong? (The only mistake I can see in my solution is typographic "+" instead of "-" which didn't affect my actual computations)
BTW, compare the solution you gave to mine and tell me which is more confusing and which is more explanatory. And would you mind giving us a diagram to buttress your explanation? I think that will throw more light to this......

mathefaro:
You still haven't told me where I got it wrong o, you got 32cm like I did after modifying your post, does that mean also wrong? (The only mistake I can see in my solution is typographic "+" instead of "-" which didn't affect my actual computations)
BTW, compare the solution you gave to mine and tell me which is more confusing and which is more explanatory. And would you mind giving us a diagram to buttress your explanation? I think that will throw more light to this......

before solving such question u must understand d image given and d lens use.....lets not make dis an issue iam waiting for ur explanation on density

Benjaminbest:
before solving such question u must understand d image given and d lens use.....lets not make dis an issue iam waiting for ur explanation on density

I'm not making it an issue here, you said I'm wrong and made it look as if I didn't know what I was doing at all and that's why I'm asking you to point out my mistake because I was and am SURE that my solution is very correct. Anyway, that's bygone, I'll give my contribution on density when I'm through with these classes ahead of me to take.
#peace

Benjaminbest:
before solving such question u must understand d image given and d lens use.....lets not make dis an issue iam waiting for ur explanation on density

Benjaminbest:
before solving such question u must understand d image given and d lens use.....lets not make dis an issue iam waiting for ur explanation on density

Benjaminbest..Mathefaro z Ryt...I/f= 1/u+1/v= 1/12=1/u+1/3u.......
solving d Fraction 1/u+1/3u=4/3u....therefore...12=4/3U...mkin u subject f formulae we hve U= 16...nd V= 3U..3*16=48...so d diatance btwen image nd object is 48-16=32cm

a simple pendulum with a period of 2.0 has it length doubled. It new period is?


If d relative density of a mental is 19 what will b d mass of 20cm of d metal wen immersed in water?


If d fundamental frequency of a closed pipe organ on a day when d speed of sound is 340ms-1 is 170hz then d length of d pipe is?


A man walk 8km north and then 5km in a direction 60 degree east of north. Find d distance from his starting point?


A household refrigerator is rated 200watts. If electricity cost 5k perkwh, what is d cost of operating it for 20days

dis is jst a little stress compare to what will b posted on dis thread two months to exam

tomoro is for chemistry....i will try to post more dan 10 questions tomoro on chemistry

iam providing new time table for d sake of our art student
Monday....................mathematics/current affair
tuesday...................physics/government
wednesday.......chemistry/c.r.s
thursday........biology/agric
friday..............english/economics
saturday......general questions
sunday.......general discussion about exams

hope am not leaving anytin out? Alryt!

So guys we will have a general test on october 26
thanks and keep following!

Benjaminbest:
a simple pendulum with a period of 2.0 has it length doubled. It new period is?
If d relative density of a mental is 19 what will b d mass of 20cm of d metal wen immersed in water?
If d fundamental frequency of a closed pipe organ on a day when d speed of sound is 340ms-1 is 170hz then d length of d pipe is?
A man walk 8km north and then 5km in a direction 60 degree east of north. Find d distance from his starting point?
A household refrigerator is rated 200watts. If electricity cost 5k perkwh, what is d cost of operating it for 20days

.....4 no 3..at fundamental,D lenght of a closed pipe is wavelenght/4= ^/4... but recall velocity= frequency * wavelenght..mkin wavelenght subject f Formula its 340/170= 2metres...
so bak 2 our closed pipe formula...Lenght=^/4.. so lenght is 2/4 = 1/2 or 0.5m

more action pls

4 number 5,Total cost = power*time/1000 d ansa mutuplied by d amount in kilowatts xo therefore , time is 20 days xo we convert it 2 hours...24 hrs mke 1 day xo 20 days is 480hrs


xo 200*480/1000=96kw...since 5k is For every kilowatt xo its 96kw*5=480k...buh recall its kwh(kilowattperhour) so 480k= N48.........D COST IS N48(forty eight naira)

good job continue i will take a bird view at ur work wen u are thru

What is the formula for calculating mid point,




Pls u guys should be using jamb syllabus too so that this lectures will b organise and not just bringing up anything from the text book