ALL CIE PHYSICS DOUBTS HERE !!!

[astarmathsandphysics]

3rd. P=Fv so 3000=180v so v=3000/180=16.66m/s
time =distance/speed=4000/16.67= 240 seconds=4 minutes

[astarmathsandphysics]

4th Dissipated heat = work done - increase in graviational potential energy =9000*40-20000*12=120000J

[astarmathsandphysics]

wavelength of visible light is about 500 nm =500*10^-9
number wavelengths in 1m is 1/(500*10^-9} =2*10^6

[ashwinkandel]

MCQ: DAY 2
Only one question today

[astarmathsandphysics]

The straw sucking question

[ashwinkandel]

MCQ Day 3: Today i got problem with 9 questions while solving 4 sets . I have attached 4 questions in this post and remaining 5 in the next post. I've got exams in 24th Nov so immediate help required.

[ashwinkandel]

Remaining Questions(5-9) attached below

[astarmathsandphysics]

For the first, take moments about the point where the floor meets the wall to get A.
For second question apply F=ma to each mass
For 2 kg 2g-T=2a
for 8 kg mass
T-6=8a
Add these to get 2g-6=10a soa=(2g-6)/10=1.4m/s^2
for third question use paralel resistor formula 1/R=1/10+1/10+1/10+1/10+1/10+1/10+1/100=0.61 so R=1/0.61 =1.6 ohms
4th quest P=IV*0.8
4000000=25000*I*0.8 so I=200A

[astarmathsandphysics]

5th question
sin theta =n*wavelength/d
d=1/300000, the width of 1 slit so sin theta =n*450*10^-9/(1/300000) =n*0.135
sin theta is at most 1 so n<=1/0.135=7.4 but since n is whole number it can be at ost 7
6th question F*0.6+F*0.6=900*0.2
F=150N
7th question half the water falls by h/2 so loss in gpe =mgh/4
8th question The excess pressure is rhog(h_2-h_1)=rho g (2h)
9th question all kinetic energy of electron is changed into potential energy of the field 1/2 mv^2 =qV=qEx so x=(1/2 mv^2)/(qE)

[angel_ak]

In the equation shown below, C is the heat capacity of a solid and T is the temperature in kelvins.

C = aT + bT³

(a) What is the unit of C?
(b) What are the units of a and b?

i found the units of C.... kgm²s^-2K^-1
but how to find that of a and b?

i know its easy but silly me

[angel_ak]

I need help in this question as well..
i did part a..
 but din understand part b at all

[ashwinkandel]

For the first question: C = aT + bT3
If the equation is valid then it is homogeneous. That means every terms should have same unit.
so unit of at= unit of c which implies that unit of a is unit of c divided by unit of T
Similarly, Find the unit for b

[angel_ak]

ohhh right!
that was quite simple.. i don know why i din come up wid the right sol 

[astarmathsandphysics]

tug boat answer

[angel_ak]

A student uses a micrometer to measure  the diameter  of a wire of length (10 +- 0.1)cm. The values obtained are 1.05mm, 1.04mm, and 1.09mm. Which of the followinf best expresses the volume of the wire?

A. 9 x 10^-8 m³
B. 8.8247 x 10^-8 m³
C. 8.825 x 10^-8 m³
D. 8.8 x 10^-8 m³