568 - Physics Questions Answers

when elevator will move in upward direction the extra Hg level will feel a down force and given that in movable condition it is 76 cm. Hg so really it will be more than 76 cm. 

I think we have to caculate change in y

since y = sin x

so dy = cosx dx = cosπ/3* π/100 = π/200

the initial velocity of car = 50j      and after turn velocity = -50i                              here i and j are the unit vectors along east and north direction

so change in velocity = -50i - 50j

its mod = 50 √2 = 70

Because in barometer the extra Hg level will experience a downward force so Hg level will decrease.

Take your right hand fingers along A and curl these fingers along B, thumb will give you an idea for A × B. for the given problem answer will be west.

|A+B|² = |A|² + |B|²+ 2A.B            (1) 

|A-B|² = |A|² + |B|² - 2A.B             (2)

on subtracting (2) by (1)

|A+B|² - |A-B|² = 4A.B

so C² = |A-B|² + 4A.B

or C² = |A-B|² +4|A||B|cos120

since cos120 is negative so C will be less than |A-B|  

for the distance upto fermi level order will be N>E>G

but  the distance between electrons is greater than fermi level so the given order is justified because now nuclear forces will be very weak.

by formula s = ut + 1/2 a t²

u = 0 [given]

so       s = 1/2 a (5)²= 25a/2       for first 5 sec.

and    s = 1/2 a (10)² = 50a        for total 10 sec. from start

so for next 5 sec. distance = 50a - 25a/2 = 75a/2

answer :  a'³ = a³ (1+ γ3)     here a' is the side of the cube after heating it

so a' = a (1+3γ)^1/3

so area increment = 6a'² -  6a² = 6a² [(1+3γ)^2/3 - 1] = 6a² [ 2γ] = 12γa²

Please submit all the questions seperately. 

λ = v/n = 300/500 

i think you are asking about increment in speed

so according to formula v'/v  = [(T+2)/T]^1/2 

or v'/v = 1 + (1/T)

so v' - v = v(1/T) = 332*1/273 =  1.22       here 332 is the speed of sound at 273K

when a machine works , you should not count gravity, for example if we raise our hand upword with uniform velocity then gravity makes no problem in it because our hand is working by our internal capabilitites

first calculate distance of 4 seconds by using s = ut + 1/2 a t²

then distance of 4.5 sec. by same formula 

difference of these 2 is the distance of 5th half sec.

but some writter consider 5th half as 1/2 +1/2+1/2+1/2+1/2 means 2.5

so they use the same formula first for 2 sec then for 2.5 sec, then their difference.

according to my opinion first is more true way to solve.

Dear Sarika please submit only one question in a box, for a new question use another box so that i could give answers more quickly.

According to the given condition

x² = 2+t

on differentiaing we get 2x dx/dt = 1

or v = 1/2x

now differentiate it again we get dv/dt = -(1/2x² )(dx/dt) = -(1/2x2 )(-1/2x) = 1/4x³                                  

This means heat can be used to make work and work done produces heat

By doing 4.2 joule work 1 cal. heat will be produced in a body so due to this 1 cal, temp. will increase

In physics heat is supplied means Q will be +ve so W will also be positive hence is correct. A system is placed in refrigrator for absorbing heat from the body, this process will have Q -ve.

It depends that either Al or water will change its density more rapidly, because Bouyancy is based on densities of solid and liquid

Answer : a, because it may be an isothermal process

b, because in isothermal process, surrounding can also give heat to the system.

c, may be the process is adiabatic

d, may be adiabatic. 

Answer :    For adiabatic process TV^γ-1 = K

so 273*V^0.25 = T*(81V)^0.25

so 273/3 = T

Answer :   Because real gases perform ideal behaviour in this range.

Answer :    Inertia about perpendicular bisector = 1/12 ML²

on increasing temperature by dT new inertia = 1/12 M[L(1+αdT)]²

so increment in inertia = 1/12 ML² [(1+αdT)²-1^-] = 1/12 ML² [ (αdT)² + 2αdT ]                 now neglect (αdT)² because it is small term

Answer :   Since temperature is already 100 degree centigrade so on increasing it further density of Al will increase rapidly in comparision to density of water so Buoyancy force will be increased.

Answer :   use the formula d₁₀₀ = d₀ / (1+γ100)   here γ=3α                    calculate α

(F-32)/9 = t/5

so F = 9t/5 + 32

on taking t = 0 we will get F = 32

thats why it makes an intercept of 32 in y axis