(D) The gravitational force between the astronaut and the asteroid.
Reason :
All the other forces given in the options, except (D), doesn't account for the motion of the astronaut. They are the forces that act between nucleons or atoms and neither of them accounts for an objects motion.
Answer:
The mantle exists above the crust of the earth
A 500 g ball swings in a vertical circle at the end of a 1.4-m-long string. when the ball is at the bottom of the circle, the tension in the string is 18 n.
Answer:
r = 0m is the Minimum distance from the axis at which the block can remain in place wothout skidding.
Explanation:
From a sum of forces:
where Ff = μ * N and 
N - m*g = 0 So, N = m*g. Replacing everything on the original equation:
(eq2)
Solving for r:

If we analyze eq2 you can conclude that as r grows, the friction has to grow (assuming that ω is constant), so the smallest distance would be 0 and the greatest 1.41m. Beyond that distance, μ has to be greater than 0.83.
River shore is located at distance

speed of the woman is given as

now the time taken by the woman to cover the distance is


for the same time interval the dog will run to and fro with speed 4.5 m/s
so the total distance moved by the dog is given by



<em>so the total distance that dog will move is 7200 m or 7.2 km</em>