Answer:
Explanation:
frequency of whistle = 1.85 x 10² = 185 Hz
frequency of beat heard = 8 beat /s . No of beat produced is equal to difference of frequencies of two sound source . Here difference is created due to Doppler effect . One of the train is moving so it will have apparent frequency which is different one from its original frequency .
When the moving train is approaching the observer , its frequency will be higher . As beat is heard at the rate of 8 beats / s , apparent frequency of approaching train will be 185 + 8 = 193 Hz .
Applying Doppler's formula of apparent frequency ,
193 = 185 x V / ( V - v ) , where V is velocity of sound and v is velocity of train .
193 V - 193 v = 185 V
193 v = 8 V
v = 8 x V / 193
= 8 x 343 / 193
= 14.21 m /s
Second possibility is that apparent velocity is less ie 185 - 8 = 177 Hz
In that case moving train will be moving away from observer . If its velocity be v
177 = 185 x V / ( V + v )
177 V + 177 v = 185 V
v = 8 x 343 / 177
= 15.50 m /s .
Density of rock = 3.23 Kg/m^3
Given:
mass of Moon rock = 8.94 kg
apparent mass of Moon rock = 6.18 kg
To Find:
density of the rock
Solution: It is a universal fact that mass of an object remains constant whether measured on earth or on moon.
Mass of rock on moon/earth = 8.94 kg
When the block is immersed in water then;
Loss in weight = weight of water displaced
Loss in weight = 8.94 - 6.18 = 2.76 kg
As we know that water has a density of 1g/cm^3 (1000kg/m^3)
Volume of water = volume of the rock = Mass/density = 2.76 kg
density of rock mass/volume = 8.94/2.76 = 3.23 Kg/m^3
Density of rock = 3.23 Kg/m^3
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Electromagnetic force. It is where alike forces ( negative, negative & positive , positive) repel and opposite forces ( negative & positive ) attract.
Hopes this helped
Answer:
material work function is 0.956 eV
Explanation:
given data
red wavelength 651 nm
green wavelength 521 nm
photo electrons = 1.50 × maximum kinetic energy
to find out
material work function
solution
we know by Einstein photo electric equation that is
for red light
h ( c / λr ) = Ф + kinetic energy
for green light
h ( c / λg ) = Ф + 1.50 × kinetic energy
now from both equation put kinetic energy from red to green
h ( c / λg ) = Ф + 1.50 × (h ( c / λr ) - Ф)
Ф =( hc / 0.50) × ( 1.50/ λr - 1/ λg)
put all value
Ф =( 6.63 ×
(3 ×
) / 0.50) × ( 1.50/ λr - 1/ λg)
Ф =( 6.63 × (3 × ) / 0.50 ) × ( 1.50/ 651×
- 1/ 521 ×)
Ф = 1.5305 ×
J × ( 1ev / 1.6 × J )
Ф = 0.956 eV
material work function is 0.956 eV
