1)In a chemical reaction the temperature rises from 60 degree celsius to 90 degr
ID: 2109041 • Letter: 1
Question
1)In a chemical reaction the temperature rises from 60 degree celsius to 90 degree celsius.What is the temperature change measured in degree Kelvin
a)30
b)273
c)333
d)363
2)A simple pendulum is made by attaching a small mass to a string.The string is hung from the ceiling and the period of the pendulum is measured.If the masshanging on the string is tripled, by what factor will the period of pendulum change?
a)3
b)0.33
c)1
d)9
3) a 1.5 kg physics book is pushed across the floor at 6.5 m/s.Iff the coefficient of kinetic friction between the book and the floor is 0.30,how long will the book slide before it stops ?
a)0.66 s
b)1.3 s
c)1.7 s
d)2.2 s
Explanation / Answer
1)initial temperature is T1 = 60 oC = 60 + 273 K = 333 K
final tamperature is T2 = 90 oC = 90 + 273 K = 363 K
the temperature change measured in degree Kelvin is
dT = (T2 - T1) = 363 - 333 = 30 K
2)The period of simple pendulum is given by
T = 2pi * (l/g)
where l is length of string and g = 9.8 m/s^2
the time period is independent of mass attached to string therefore the period does not change
3)mass of physics book is m = 1.5 kg
initial speed of book is u = 6.5 m/s
coefficient of friction is u = 0.30
the acceleration of book is a = u * g
where g = 9.8 m/s^2
when finnal velocity is zero then distance travelled is
S = (v^2 - u^2/2a)
where v = 0
let the time taken to stop be t
we know that
S = ut + (1/2)at^2
solving the above equation for time
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