Let the mass of 2500 kg car be
and it's velocity be
and the mass of 1500 kg car be
and it's velocity be
.
After the bumping the mass be M and it's velocity be V.
By law of conservation of momentum we have

2500 * 5 + 1500 * 1=4000 * V
V = 14000/4000 = 7/2 = 3.5 m/s
So the velocity of the two-car train = 3.5 m/s
Answer:

Explanation:
As per Kepler's III law we know that time period of revolution of satellite or planet is given by the formula

now for the time period of moon around the earth we can say

here we know that


= mass of earth
Now if the same formula is used for revolution of Earth around the sun

here we know that


= mass of Sun
now we have




Answer:
537 N
Explanation:
The force due to gravity of a planet is:
F = GMm / r²
where G is the universal gravitational constant
M is the mass of the planet
m is the mass of the object
and r is the distance between the object and the center of the planet
On Earth, you weigh 716 N, so:
716 N = GMm / r²
On planet X:
F = G (3M) m / (2r)²
F = 3/4 GMm / r²
F = 3/4 (716 N)
F = 537 N