Physics, Chemistry and Biology: Post your doubts here!

[waleed82]

can any 1 tell me about

vectors and scalars??????

 

[Iridescent]

scalar is da 1 which only has magnitude e.g distance, while vector is da 1 which has magnitude n direction e.g displacement.

 

[waleed82]

thankz alot..........

 

[waleed82]

Q1: A train increases its speed steadily from 10m/s to 20m/s in 1 minute.

a) What is its average speed during this time in m/s?
b) How far does it travel while increasing its speed?

Q2: An aircraft travelling at 600 km/h accelerates steadily at 10 km/h per second.
Taking the speed of sound as 1100 km/h at the aircraft's altitude , how long
will it take to reach the ''sound barrier''?

Q3: If a bus travelling at 20 m/s is subject a steady deceleration of 5 m/s2 , how long will it take to come to rest?

(guyz can any 1 of u can solve dis ques 4 me???????)

 

[Iridescent]

Q1: A train increases its speed steadily from 10m/s to 20m/s in 1 minute.

a) What is its average speed during this time in m/s?
b) How far does it travel while increasing its speed?

Q2: An aircraft travelling at 600 km/h accelerates steadily at 10 km/h per second.
Taking the speed of sound as 1100 km/h at the aircraft's altitude , how long
will it take to reach the ''sound barrier''?

Q3: If a bus travelling at 20 m/s is subject a steady deceleration of 5 m/s2 , how long will it take to come to rest?

(guyz can any 1 of u can solve dis ques 4 me???????)

Q1. a) av.speed= (v+u)/2
=15m/s
b) a=(v-u)/t
a=(20-10)/60
a=(1/6)m/s2
distance=ut+1/2at2
=(10*60)+1/2*(1/6)*(60)2
=600+300
=900m

Q2. t=(v-u)/a
t=(1100-600)/10
t=500/10
t=50h

Q3. t=(v-u)/a
t=(0-20)/-5
t=-20/-5
t=4s.

 

[waleed82]

thankz!!!!!!!!!!!!!!

 

[semsemhosam]

I am having problem with moments. Especially stable,neutral and unstable equilibrium..plx help!!!!!!!!!!

moment is the turning effect , it's in equilibrium when the clockwise moment is equal to the anticlockwise moment or in other words force1 x distance1 =force2 x distance2 (p.s. the distance is from the pivot to the mass or force ) .. hope that helps

 

[Spirit95]

Q1: A train increases its speed steadily from 10m/s to 20m/s in 1 minute.

a) What is its average speed during this time in m/s?
b) How far does it travel while increasing its speed?

Q2: An aircraft travelling at 600 km/h accelerates steadily at 10 km/h per second.
Taking the speed of sound as 1100 km/h at the aircraft's altitude , how long
will it take to reach the ''sound barrier''?

Q3: If a bus travelling at 20 m/s is subject a steady deceleration of 5 m/s2 , how long will it take to come to rest?

(guyz can any 1 of u can solve dis ques 4 me???????)

The person who answered these questions for you did them all right. However, I noticed that for Q1-b) he used a very complex and time-consuming formula. I have a better formula and an easier one to use, d=((v+u)/2)t. Therefore, you add both initial speed and final speed to get 30 m/s. You then divide by 2 to get avg. speed, which is 15 m/s and you then multiply by time, which is 60 s. You will get 900 m.

 

[waleed82]

The person who answered these questions for you did them all right. However, I noticed that for Q1-b) he used a very complex and time-consuming formula. I have a better formula and an easier one to use, d=((v+u)/2)t. Therefore, you add both initial speed and final speed to get 30 m/s. You then divide by 2 to get avg. speed, which is 15 m/s and you then multiply by time, which is 60 s. You will get 900 m.

oh ya datz more better btw r u doin IGCSE or GCE

 

[Spirit95]

oh ya datz more better btw r u doin IGCSE or GCE

I am applying or my IGCSE this May/June.

 

[waleed82]

I am applying or my IGCSE this May/June.

no man m sayin dat r u studin IGCSE physics of GCE physics

 

[Spirit95]

no man m sayin dat r u studin IGCSE physics of GCE physics

I understand, and that's why I am telling you I am applying for IGCSE, so obviously, I study IGCSE Physics.

 

[waleed82]

oho...kkk.......so r u living in pakistan????

 

[Spirit95]

oho...kkk.......so r u living in pakistan????

No, my location is United Arab Emirates, which apparently, is next to where you live.

 

[waleed82]

oho ya.....kkkk

so,how many subj. will u give dis may/june

 

[waleed82]

The potential difference across the variable resistor is 7.0 V and that across the

ammeter is zero.

(i) Calculate the potential difference across the magnetising coil.

potential difference = .................................

(ii) State the general principle used in making this calculation.

...................................................................................................................................

...................................................................................................................................

 

[Spirit95]

The potential difference across the variable resistor is 7.0 V and that across the

ammeter is zero.

(i) Calculate the potential difference across the magnetising coil.

potential difference = .................................

(ii) State the general principle used in making this calculation.

...................................................................................................................................

...................................................................................................................................

I am taking 8 subjects this year.

Anyway, wasn't there a diagram provided with this question? And what is the paper you got it from?

 

[waleed82]

no btw da paper iz

http://www.xtremepapers.com/CIE/Cambridge IGCSE/0625 - Physics/0625_w02_qp_3.pdf

check out ques no.7 (c)

 

[semsemhosam]

can any 1 tell me about

vectors and scalars??????

vectors are quantities which has both magnitude and direction eg : velocity , the velocity is constant when your moving in one direction with the same speed , once you change direction or speed , it changes . scalars has only magnitude eg: speed , is the distance moved per unit time , without consideration of direction . hope that helps

 

[Minato112]

The person who answered these questions for you did them all right. However, I noticed that for Q1-b) he used a very complex and time-consuming formula. I have a better formula and an easier one to use, d=((v+u)/2)t. Therefore, you add both initial speed and final speed to get 30 m/s. You then divide by 2 to get avg. speed, which is 15 m/s and you then multiply by time, which is 60 s. You will get 900 m.

Yeah Indeed that formula saves time