Physics, Chemistry, Mathematics Forums

Why 1-Bromo-bicyclo [2.2.1]-heptane does not show elimination reaction in presence of a base?

:-D  3 Questions on H & T

1. A straight bar AC of uniform cross-section consists of two parts AB and BC each 50cm
long at 20 deg. celcius. AB is made of iron and BC of aluminium. The bar is pivoted about a point 37.65cm from A and rests just on a support at A. The bar is then heated uniformly and at a certain temperature the end C tilts downward. Calculate the temprature with the aid of the following given data :

Density of iron at 20 deg. celcius = 7.86 gm/cc
Density of aluminium at 20 deg. celcius = 2.65 gm/cc
Linear coefficient of iron = 0.000012 /K
Linear coefficient of aluminium = 0.000025 /K

2.An astronaut takes a cylinder of volume 10 litres containing nitogen gas at temperature of
300K and pressure 50 atm. He makes a hole of area 1 cm² in this cylinder and places it in open space .Estimate the time it would take for the cylinder to become empty.
Boltzmann const = 1.38 x 10^-23.Explain your answer.

3. A hot body placed in air is cooled according to Newton's law of cooling, the rate of decrease of temprature being K times the temprature difference from the suuroundings . Starting from t = 0, Find the time in which the body loses half the maximum heat it can lose.

    You are sitting on a seat facing forward an aeroplane with its wings parallel to the ground. the window shades of the aeroplane are closed, and the vibration of the plane is negligible.When you place a ring on the end of a necklace chain and hold the other end in front of you, you notice that the chain and the ring hang vertically and point directly to the floor of the aeroplane. whatis true about the aeroplane

1. the aeroplane is at rest
2. the aeroplane is moving witha constant velocity
3. the aeroplane is increasing in speed
4. the aeroplane is decreasing in speed

can anyody help me out for the mechanism of addition of 2 moles of CH₃COOH to one mole of 2-butyne.

A flat car of mass m_o starts moving to the right due to a constant horizontal force F . Sand spills on the flat car from a stationary hooper . the rate of loading is constant and equals u kg/s . find the time dependence of the velocity and the acceleration of flat car in the process of loading . neglect friction.

can anybody tell me the general method to solve the questions of the variable mass ?

i encountered this problem in this years UP technical university entrance examination...

lim _x->0  (x^x)^x

any idea anyone?

1)if linear momentum of a sytem is constant does center of mass remain at rest?(please explain)

2)let linear pomentum =mass*speed.

i think that linear pomentum of the system must remain constant if a external force acts that does not alter the magnitude of the velocity i.e. the speed.is my logic right?is my logic valid for a single particle?

1) 4 modifications r suggested in the lens formula to include the effect of thickness 't' of the lens.which one is likely to be correct? (H.C. VERMA PAGE 411)
A)(1/v)-(1/u)=(t/uf)
B)(t/v^2)-(1/u)=(1/f)
C)(v-t)^-1 +(u+t)^-1 =(1/f)
D)(1/v)-(1/u)+(t/uv)=t/f

TELL ME HOW 2 PROCEED?


2)QUESTION 14 IN SAME PAGE.
I'M GETTING, FOR MU>1 ANS =D
FOR MU<1 ANS =C
PLEASE LET ME KNOW U'R OPINION.

A particle moving along the X axis is acted upon by a single force F=F_oe^-kx where F_o and k are constants. The particle is released from rest at x=0. It will attain a maximum kinectic energy of
    a) F_o/k
    b) F_o/e^k
    c) kF_o
    d) (kF_o)²/2