Given :
Height from which ball is dropped , h = 40 m .
Acceleration due to gravity , g= 10 m/s² .
Initial velocity , u = 0 m/s .
To Find :
Velocity when ball covered 20 m and velocity when it hit the ground .
Solution :
Now , height when ball covered 20 m distance is , 40 - 20 = 20 m .
By equation of motion :
Now , distance covered when body reaches ground is , 40 m .
Putting value h = 40 m in above equation , we get :
Hence , this is the required solution .
A & C
Explanation:
The combination of the earth's weak gravity and its closeness to the sun does not allow it to hold hydrogen and helium gases in its atmosphere. Its relative closeness to the sun means it is hot enough such that the helium and hydrogen molecules would have high kinetic energy. Remember that gravity acts strongly on larger masses, therefore it would require very strong gravity to have an influence on lighter gas molecules like hydrogen and helium let alone when they have a high kinetic energy. This means these molecules can easily escape the earth’s atmosphere into space.
Planets that are larger (meaning they have a stronger gravity) and farther from the sun (meaning these molecules won't have a very high kinetic energy) are able to hold these lighter gases in their atmosphere. Examples of such planets are Jupiter.
Learn More:
For more on gravity check out;
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The law of conservation of linear momentum says that when objects collide, the total initial momentum equals the total final momentum.
The momentum of a body is given by the product of mass and velocity of the object.
The array of colors observed when viewing films of soap are caused by the interference, and from the reflections of light from two nearby surfaces (outer surface and inner surface). Among the choices, the closest answer would be B. reflection, refraction, and interference.
11.2 = 0.550u + 1/2 * 9.8 * (0.550)^2
u = 17.67 m/s
