Answer:
The magnitude of the frictional force is 
Explanation:
From the question we are told that
The force exerted on the box is 
Generally for the box to remain at rest then it means that the frictional force is greater than or equal to the force applied to move it i.e

=> 
Answer:
:)
Explanation:
The strength of the gravitational force between two objects depends on two factors, mass and distance. the force of gravity the masses exert on each other. If one of the masses is doubled, the force of gravity between the objects is doubled. increases, the force of gravity decreases.
<span>Answer:
NASA in US using its super powerful telescope checks all the meteorites ,asteroids that may land on Earth. It deflects the asteroids ,meteorites from their respective path using copper ball . But it is not wholly practical as sometimes these meteorites get enter into key hole .</span>