Answer:
finding Cepheid variable and measuring their periods.
Explanation:
This method is called finding Cepheid variable and measuring their periods.
Cepheid variable is actually a type of star that has a radial pulsation having a varying brightness and diameter. This change in brightness is very well defined having a period and amplitude.
A potent clear link between the luminosity and pulsation period of a Cepheid variable developed Cepheids as an important determinants of cosmic criteria for scaling galactic and extra galactic distances. Henrietta Swan Leavitt revealed this robust feature of conventional Cepheid in 1908 after observing thousands of variable stars in the Magellanic Clouds. This in fact turn, by making comparisons its established luminosity to its measured brightness, allows one to evaluate the distance to the star.
Answer:
electricity
If a rod is charged it is because of the electrical force acting on it
Answer:
Explanation:
Btu of British thermal unit is a unit of heat. The relation between btu/year and watts is given by :
So, 
is equal to 11 kW. Hence, the correct option is (d).
Answer:
Speed of the car 1 =
Speed of the car 2 =
Explanation:
Given:
Mass of the car 1 , M₁ = Twice the mass of car 2(M₂)
mathematically,
M₁ = 2M₂
Kinetic Energy of the car 1 = Half the kinetic energy of the car 2
KE₁ = 0.5 KE₂
Now, the kinetic energy for a body is given as
where,
m = mass of the body
v = velocity of the body
thus,
or
or
or
or
or
.................(1)
also,
or
or
or
or
or
or
or
or
and, from equation (1)
Hence,
Speed of car 1 =
Speed of car 2 =
Answer:
20 kg
Explanation:
remember the equation f=ma.
100 N=force
5 m/s2= acceleration
so you need to divide force by acceleration: 100 N/ 5 m/s2= 20 kg, to get the mass.
