<h2>QUESTION:- </h2>
➜what is kepler's law??

Kepler gave the three laws or theorems of motion of the orbitals bodies

This law state that the celestial bodies revolves around the stars in elliptical orbit and star as a single focus.
Example :- Earth revolves around the Sun as assuming it as single focus
This also shows that earth revolves around the sun in elliptical orbit.

Area covered by the planet is equal in equal duration of time irrespective of the position of the planet.
It also states that Angular momentum is constant
As Angular momentum is constant it means areal velocity is also constant.

where:-
A is the area.
T is the time.
L is the angular momentum.
M is the mass of the body.

square of the time of the revolution is directly proportional to the cube of the distance between the planet and star in Astronomical unit.

where:-
T = time of revolution
a is the distance between the planet and star.

Answer:
Kr
Explanation:
the element that is in group 18 is noble gasses. the elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og).
Answer:
404K
Explanation:
Data given, Kinetic Energy.K.E=8.37*10^-21J
Note: as the temperature of a is increase, the rate of random movement will increase, hence leading to more collision per unit time. Hence we can say that the relationship between the kinetic energy and the temperature is a direct variation.
This relationship can be expressed as

where K is a constant of value 1.38*10^-23
Hence if we substitute the values, we arrive at

converting to degree we have 
Answer:
Part a)

Part b)

Explanation:
Part a)
As we know that the magnetic force on the current carrying wire is given as

so we have


so we have

Part b)
Now magnetic field is changed to 0.55 T
so we will have


Answer:
12.2 m/s
Explanation:
Initial momentum = final momentum
In the x direction:
(900 kg) (15.0 m/s) = (900 kg + 750 kg) vx
vx = 8.18 m/s
In the y direction:
(750 kg) (20.0 m/s) = (900 kg + 750 kg) vy
vy = 9.09
The magnitude of the velocity is therefore:
v = √(vx² + vy²)
v = 12.2 m/s